A previously healthy 27-year-old man comes to the physician because of a 3-week history of anxiety, diarrhea, and a 4.1-kg (9-lb) weight loss. On questioning, he also reports that he noticed a painless mass on his left testicle 2 weeks ago. His pulse is 110/min and irregular and blood pressure is 150/70 mm Hg. Examination shows diaphoresis and a fine tremor of the outstretched fingers. Testicular examination shows a 3-cm, firm, nontender mass on the left scrotum that does not transilluminate. This patient's underlying condition is most likely to be associated with which of the following findings?
Q22
A 6-year-old boy is brought to the physician because of worsening headaches and a rash for 2 weeks. His mother reports that the rash started on his abdomen and diffusely spread to other areas. Over the past 2 months, he has had recurrent episodes of otitis media. Examination shows a diffuse, erythematous, papular rash involving the groin, abdomen, chest, and back. His cervical lymph nodes are palpable bilaterally. An x-ray of the skull shows well-defined lytic lesions of the left occipital bone and the mastoid bone. Electron microscopy of a biopsy of the patient's posterior cervical lymph nodes shows polygonal cells with organelles shaped like tennis rackets. The cells stain positive for S-100. Clonal proliferation of which of the following types of cells is most likely seen on microscopy?
Q23
A 67-year-old woman comes to the physician because of a 3-week history of fatigue and worsening back and abdominal pain. During this period, she has also had excessive night sweats and a 4.6-kg (10-lb) weight loss. She has had swelling of the neck for 3 days. She does not smoke or drink alcohol. Vital signs are within normal limits. Physical examination shows a 4-cm, supraclavicular, nontender, enlarged and fixed lymph node. The spleen is palpated 2 cm below the left costal margin. Laboratory studies show:
Hemoglobin 10.4 g/dL
Mean corpuscular volume 87 μm3
Leukocyte count 5,200/mm3
Platelet count 190,000/mm3
Serum
Lactate dehydrogenase 310 U/L
A CT scan of the thorax and abdomen shows massively enlarged paraaortic, axillary, mediastinal, and cervical lymph nodes. Histopathologic examination of an excised cervical lymph node shows lymphocytes with a high proliferative index that stain positive for CD20. Which of the following is the most likely diagnosis?
Q24
A 71-year-old woman comes to the physician with a 2-month history of fatigue, anorexia, abdominal swelling, shortness of breath, and a 5-kg (11-lb) weight loss. She appears chronically ill. Examination shows jaundice, bilateral temporalis muscle wasting, hepatosplenomegaly, and tense ascites. Ultrasonography of the abdomen shows multiple hepatic masses and enlargement of the portal vein. Which of the following is the most likely cause of these masses?
Q25
A 55-year-old woman comes to the physician with concerns about swelling and pain in her right breast. Physical examination shows erythema and prominent pitting of the hair follicles overlying the upper and lower outer quadrants of the right breast. There are no nipple changes or discharge. A core needle biopsy shows invasive carcinoma of the breast. Which of the following is the most likely explanation for this patient's skin findings?
Q26
A 25-year-old man presents with a mass on his neck. He says that he first noticed the mass a few weeks ago while taking a shower. Since then, the mass has not increased in size. He denies any pain or difficulty in swallowing. Past medical history is unremarkable. Family history is significant for his father who had his thyroid removed when he was around his age but doesn’t know why. Review of systems is significant for occasional episodes of anxiety that include a pounding headache, racing heart, and sweating. His vital signs include: pulse 88/min, blood pressure 133/87 mm Hg, temperature 37.2°C (99.0°F), and respiratory rate 14/min. He is 183 cm (6 ft 2 in) tall with long extremities. On physical examination, the patient appears cachectic. There is a palpable 4 cm x 4 cm nodule present on the left lobe of the thyroid. Which of the following is the most likely thyroid pathology in this patient?
Q27
A 65-year-old African-American man presents to your office with dysphagia. He reports that he has found it progressively more difficult to swallow food over the past year. At the time of presentation, he is able to eat only soup. Social history is significant for asbestos exposure, multiple daily drinks of hard alcohol, and a 70 pack-year smoking history. What would you most expect to see on an esophageal biopsy of this patient?
Q28
An 8-year-old girl is brought to the clinic by her parents for fever and easy bruising. Her parents report that the child has been bruising easily ever since an upper respiratory infection 3 months ago. For example, a bump into the table resulted in a large bruise on the side of her hip for a week. Three days ago, her mother noticed that the child felt warm and subsequently measured a temperature of 101.8°F (38.8°C) that did not respond to acetaminophen. The patient denies any chills, cough, rhinorrhea, pharyngitis, sick contacts, headache, or urinary symptoms. A physical examination demonstrates a nontender, firm, and rubbery node along her left neck and splenomegaly. Laboratory findings are shown below:
Leukocyte count and differential:
Leukocyte count: 19,000/mm³
Neutrophils: 39%
Bands: 12%
Eosinophils: 2%
Basophils: 0.5%
Lymphocytes: 40%
Monocytes: 6.5%
Hemoglobin: 9.7 g/dL
Platelet count: 100,000/mm³
Mean corpuscular hemoglobin concentration: 30%
Mean corpuscular volume: 76 μm³
Reticulocyte count: 0.7%
What cytogenetic abnormality would be most likely in this patient?
Q29
A 19-year-old man comes to the physician because of a 2-day history of blood-speckled stools and a protruding rectal mass. He has no abdominal pain, altered bowel habits, or fever. His mother has inflammatory bowel disease. His vital signs are within normal limits. Examination shows multiple, small, hyperpigmented maculae on the lips, buccal mucosa, palms, and soles. The abdomen is soft with no organomegaly. Rectal examination shows a 4-cm pedunculated polyp with superficial excoriations on the mucosa. A colonoscopy shows 14 polyps. A biopsy shows hamartomatous mucosal polyps. This patient's diagnosis is most likely?
Q30
A 42-year-old woman is seen by her primary care physician for her annual checkup. She has no current concerns and says that she has been healthy over the last year except for a bout of the flu in December. She has no significant past medical history and is not currently taking any medications. She has smoked 1 pack per day since she was 21 and drinks socially with her friends. Her family history is significant for prostate cancer in her dad when he was 51 years of age and ovarian cancer in her paternal aunt when she was 41 years of age. Physical exam reveals a firm, immobile, painless lump in the upper outer quadrant of her left breast as well as 2 smaller nodules in the lower quadrants of her right breast. Biopsy of these lesions shows small, atypical, glandular, duct-like cells with stellate morphology. Which of the following pathways is most likely abnormal in this patient?
Neoplasia US Medical PG Practice Questions and MCQs
Question 21: A previously healthy 27-year-old man comes to the physician because of a 3-week history of anxiety, diarrhea, and a 4.1-kg (9-lb) weight loss. On questioning, he also reports that he noticed a painless mass on his left testicle 2 weeks ago. His pulse is 110/min and irregular and blood pressure is 150/70 mm Hg. Examination shows diaphoresis and a fine tremor of the outstretched fingers. Testicular examination shows a 3-cm, firm, nontender mass on the left scrotum that does not transilluminate. This patient's underlying condition is most likely to be associated with which of the following findings?
A. Elevated serum AFP
B. Elevated serum hCG (Correct Answer)
C. Elevated serum TSH
D. Proptosis on exophthalmometry
E. Positive urine metanephrines
Explanation: ***Elevated serum hCG***
- The patient presents with symptoms of **hyperthyroidism** (anxiety, weight loss, tachycardia, tremor, diaphoresis) and a **testicular mass**.
- Some **testicular germ cell tumors**, particularly **choriocarcinoma** and some **mixed germ cell tumors**, can produce **hCG**, which has structural similarity to TSH and can stimulate the thyroid gland, leading to **paraneoplastic hyperthyroidism**.
- **Serum hCG** is an important tumor marker for germ cell tumors and would be elevated in this clinical scenario.
*Elevated serum AFP*
- **Alpha-fetoprotein (AFP)** is a tumor marker often elevated in **non-seminomatous germ cell tumors** like **yolk sac tumors** and **embryonal carcinomas**.
- While AFP may be elevated in some testicular tumors, it does not explain the hyperthyroid symptoms, as hCG (not AFP) has TSH-like activity.
*Elevated serum TSH*
- In **hyperthyroidism**, the **thyroid stimulating hormone (TSH)** level is typically **suppressed** due to negative feedback from high thyroid hormone levels.
- An elevated TSH would indicate **primary hypothyroidism**, which contradicts the patient's clinical presentation.
*Proptosis on exophthalmometry*
- **Proptosis** (exophthalmos) is a common finding in **Graves' disease**, an autoimmune cause of hyperthyroidism.
- However, the presence of a **testicular mass** strongly suggests a paraneoplastic etiology for the hyperthyroidism, making Graves' disease less likely as the primary underlying condition.
*Positive urine metanephrines*
- **Urine metanephrines** are markers elevated in **pheochromocytoma**, a tumor of the adrenal medulla that secretes catecholamines.
- While pheochromocytoma can cause hypertension, tachycardia, and anxiety, it does not typically present with a testicular mass or directly cause weight loss through a thyroid-like mechanism.
Question 22: A 6-year-old boy is brought to the physician because of worsening headaches and a rash for 2 weeks. His mother reports that the rash started on his abdomen and diffusely spread to other areas. Over the past 2 months, he has had recurrent episodes of otitis media. Examination shows a diffuse, erythematous, papular rash involving the groin, abdomen, chest, and back. His cervical lymph nodes are palpable bilaterally. An x-ray of the skull shows well-defined lytic lesions of the left occipital bone and the mastoid bone. Electron microscopy of a biopsy of the patient's posterior cervical lymph nodes shows polygonal cells with organelles shaped like tennis rackets. The cells stain positive for S-100. Clonal proliferation of which of the following types of cells is most likely seen on microscopy?
A. Eosinophils
B. Plasma cells
C. Natural killer cells
D. Langerhans cells (Correct Answer)
E. B cells
Explanation: ***Langerhans cells***
- The presence of **Birbeck granules** (tennis racket-shaped organelles) on electron microscopy and **S-100 positivity** are pathognomonic for **Langerhans cells histiocytosis (LCH)**.
- The clinical presentation with **lytic bone lesions**, **recurrent otitis media**, **headaches**, and a **diffuse rash** in a child is highly characteristic of LCH.
*Eosinophils*
- While **eosinophils** can be present in some forms of LCH, the primary clonal proliferation in LCH is of Langerhans cells, not eosinophils themselves.
- **Eosinophilia** is a common finding in various allergic and parasitic conditions, but it does not explain the widespread lytic bone lesions or the specific electron microscopy and immunohistochemical findings.
*Plasma cells*
- **Plasma cell proliferations** are typically associated with **multiple myeloma** or **plasmacytomas**, presenting with monoclonal gammopathy and different types of bone lesions (punch-out lesions often without an osteoblastic rim).
- Plasma cells do not contain Birbeck granules and are negative for S-100.
*Natural killer cells*
- **Natural killer (NK) cell proliferations** are rare and typically manifest as lymphomas, often aggressive, with different clinical features and no association with Birbeck granules or S-100 positivity.
- NK cell lymphomas would not present with multifocal lytic bone lesions as described.
*B cells*
- **B-cell proliferations** lead to **lymphomas** or **leukemias**, which present with different clinical features like prominent lymphadenopathy, splenomegaly, or bone marrow infiltration.
- B cells do not contain Birbeck granules, are typically CD20 positive, and are negative for S-100.
Question 23: A 67-year-old woman comes to the physician because of a 3-week history of fatigue and worsening back and abdominal pain. During this period, she has also had excessive night sweats and a 4.6-kg (10-lb) weight loss. She has had swelling of the neck for 3 days. She does not smoke or drink alcohol. Vital signs are within normal limits. Physical examination shows a 4-cm, supraclavicular, nontender, enlarged and fixed lymph node. The spleen is palpated 2 cm below the left costal margin. Laboratory studies show:
Hemoglobin 10.4 g/dL
Mean corpuscular volume 87 μm3
Leukocyte count 5,200/mm3
Platelet count 190,000/mm3
Serum
Lactate dehydrogenase 310 U/L
A CT scan of the thorax and abdomen shows massively enlarged paraaortic, axillary, mediastinal, and cervical lymph nodes. Histopathologic examination of an excised cervical lymph node shows lymphocytes with a high proliferative index that stain positive for CD20. Which of the following is the most likely diagnosis?
A. Hairy cell leukemia
B. Adult T-cell lymphoma
C. Diffuse large B-cell lymphoma (Correct Answer)
D. Marginal zone lymphoma
E. Follicular lymphoma
Explanation: ***Diffuse large B-cell lymphoma***
- The patient presents with **B symptoms** (fever, night sweats, weight loss), rapid progression, generalized **lymphadenopathy** (cervical, supraclavicular, paraaortic, axillary, mediastinal), **splenomegaly**, and elevated **LDH**.
- **Histopathologic examination** showing lymphocytes with a **high proliferative index** and positive **CD20 staining** confirms a B-cell lymphoma with aggressive features, highly characteristic of DLBCL.
*Hairy cell leukemia*
- This condition typically presents with **splenomegaly** and **pancytopenia**, but **lymphadenopathy** is rare and often absent.
- The characteristic "hairy cells" are identified by specific markers (CD103, CD123, CD25), and a **high proliferative index** is not a feature.
*Adult T-cell lymphoma*
- This lymphoma is associated with **HTLV-1 infection** and often presents with hypercalcemia, skin lesions, and generalized lymphadenopathy, but it is a **T-cell lymphoma**.
- The **CD20 positivity** in the histology rules out a T-cell lineage lymphoma.
*Marginal zone lymphoma*
- This is an **indolent B-cell lymphoma** that typically progresses slowly and is often associated with chronic inflammation or autoimmune diseases.
- The patient's aggressive symptoms, rapid progression, significant **B symptoms**, and **high proliferative index** are not consistent with indolent lymphoma.
*Follicular lymphoma*
- This is also an **indolent B-cell lymphoma** characterized by a follicular growth pattern and usually presents with painless lymphadenopathy.
- The rapid onset of symptoms, significant **B symptoms**, and elevated **LDH** indicate an aggressive lymphoma, which is not typical of follicular lymphoma.
Question 24: A 71-year-old woman comes to the physician with a 2-month history of fatigue, anorexia, abdominal swelling, shortness of breath, and a 5-kg (11-lb) weight loss. She appears chronically ill. Examination shows jaundice, bilateral temporalis muscle wasting, hepatosplenomegaly, and tense ascites. Ultrasonography of the abdomen shows multiple hepatic masses and enlargement of the portal vein. Which of the following is the most likely cause of these masses?
A. Hyperplasia of atypical bile duct tissue
B. Metastatic spread of malignant cells from the colon (Correct Answer)
C. Lymphoproliferative disorder of hepatic sinusoids
D. Proliferation of hepatic capillaries
E. Malignant transformation of hepatocytes
Explanation: ***Metastatic spread of malignant cells from the colon***
- The constellation of symptoms (fatigue, anorexia, weight loss, jaundice, hepatosplenomegaly, ascites) and multiple hepatic masses in an elderly patient is highly suggestive of **widespread metastatic disease** to the liver.
- The **colon** is a very common primary site for cancers that metastasize to the liver due to its venous drainage via the portal system.
*Hyperplasia of atypical bile duct tissue*
- This description typically refers to **cholangiocarcinoma**, which usually presents as a single mass or a few localized masses, not multiple widespread hepatic lesions and marked hepatosplenomegaly.
- While cholangiocarcinoma can cause jaundice and weight loss, the extensive nature of the findings in this patient makes widespread metastases more likely.
*Lymphoproliferative disorder of hepatic sinusoids*
- This could refer to conditions like **hepatic lymphoma**, which can cause hepatosplenomegaly and liver masses.
- However, primary hepatic lymphoma is rare, and the symptoms are often more specific to lymphadenopathy or systemic B symptoms, rather than presenting primarily with multiple liver masses and extensive symptomatology without other clear signs of lymphoma.
*Proliferation of hepatic capillaries*
- This typically describes **hemangiomas**, which are benign vascular tumors of the liver.
- Hemangiomas are usually asymptomatic, found incidentally, and do not cause significant systemic symptoms like jaundice, cachexia, or hepatosplenomegaly, nor do they typically present as widespread "multiple hepatic masses" in this clinical context.
*Malignant transformation of hepatocytes*
- This refers to **hepatocellular carcinoma (HCC)**, which can present with similar symptoms and liver masses.
- However, HCC more commonly arises in the context of chronic liver disease (e.g., cirrhosis), and while it can be multifocal, "multiple hepatic masses" in a patient without a clear history of liver disease, but with signs of systemic malignancy, make metastatic carcinoma more probable.
Question 25: A 55-year-old woman comes to the physician with concerns about swelling and pain in her right breast. Physical examination shows erythema and prominent pitting of the hair follicles overlying the upper and lower outer quadrants of the right breast. There are no nipple changes or discharge. A core needle biopsy shows invasive carcinoma of the breast. Which of the following is the most likely explanation for this patient's skin findings?
A. Infiltration of the lactiferous ducts
B. Obstruction of the lymphatic channels (Correct Answer)
C. Involution of the breast parenchyma and ductal system
D. Tightening of the suspensory ligaments
E. Bacterial invasion of the subcutaneous tissue
Explanation: ***Obstruction of the lymphatic channels***
- The characteristic skin findings of **erythema** and **prominent pitting of the hair follicles** (peau d'orange) in the context of breast cancer are pathognomonic for **inflammatory breast cancer**.
- This appearance results from **tumor cells obstructing dermal lymphatic channels**, leading to localized fluid accumulation or lymphedema in the skin.
*Infiltration of the lactiferous ducts*
- While **ductal carcinoma** is a common type of breast cancer, infiltration of the lactiferous ducts alone doesn't directly cause a diffuse inflammatory skin change like *peau d'orange*.
- This type of infiltration often leads to nipple discharge or retraction, which are specifically noted as absent in this patient.
*Involution of the breast parenchyma and ductal system*
- **Involution** is a normal physiological process of breast tissue regression, typically with aging, and does not cause **inflammatory skin changes** or focal swelling.
- It is not associated with breast cancer or its characteristic skin manifestations.
*Tightening of the suspensory ligaments*
- Tightening of the **Cooper's ligaments** can occur with tumor infiltration, leading to skin dimpling or retraction, but not the diffuse **edema** and **erythema** characteristic of *peau d'orange*.
- This typically creates a puckering effect rather than the widespread pitting seen in this case.
*Bacterial invasion of the subcutaneous tissue*
- **Bacterial infections** (e.g., cellulitis) would typically present with more acute signs of infection such as fever, warmth, and rapidly spreading erythema, often with tenderness.
- The presented symptoms are chronic and associated with an underlying malignancy, rather than an infectious process.
Question 26: A 25-year-old man presents with a mass on his neck. He says that he first noticed the mass a few weeks ago while taking a shower. Since then, the mass has not increased in size. He denies any pain or difficulty in swallowing. Past medical history is unremarkable. Family history is significant for his father who had his thyroid removed when he was around his age but doesn’t know why. Review of systems is significant for occasional episodes of anxiety that include a pounding headache, racing heart, and sweating. His vital signs include: pulse 88/min, blood pressure 133/87 mm Hg, temperature 37.2°C (99.0°F), and respiratory rate 14/min. He is 183 cm (6 ft 2 in) tall with long extremities. On physical examination, the patient appears cachectic. There is a palpable 4 cm x 4 cm nodule present on the left lobe of the thyroid. Which of the following is the most likely thyroid pathology in this patient?
A. Follicular adenoma
B. Medullary carcinoma (Correct Answer)
C. Giant cell thyroiditis
D. Papillary carcinoma
E. Anaplastic carcinoma
Explanation: ***Medullary carcinoma***
- This patient's presentation with a **neck mass**, family history of thyroid removal at a young age, and episodic symptoms of **pounding headache, racing heart, and sweating** (suggestive of **pheochromocytoma**) strongly points to medullary thyroid carcinoma (MTC) as part of **Multiple Endocrine Neoplasia type 2B (MEN 2B)**.
- The **tall stature, long extremities, and cachectic appearance** (Marfanoid habitus) are characteristic features of **MEN 2B syndrome**, which consists of MTC, pheochromocytoma, Marfanoid habitus, and mucosal neuromas.
- MTC arises from **parafollicular C cells** and secretes **calcitonin**; it is associated with **RET proto-oncogene mutations** in hereditary cases.
*Follicular adenoma*
- While follicular adenomas can present as a **solitary thyroid nodule**, they are **benign** and do not present with the systemic symptoms (anxiety-like episodes, palpitations, headaches) or family history suggestive of a hereditary cancer syndrome.
- There is no association with **pheochromocytoma** or **Marfanoid habitus**.
*Giant cell thyroiditis*
- **Giant cell thyroiditis (subacute thyroiditis/De Quervain thyroiditis)** is characterized by a **painful, tender thyroid** nodule, often preceded by a viral upper respiratory infection.
- The patient's nodule is described as **non-painful**, and his symptoms do not align with the typical course of thyroiditis (fever, elevated ESR, transient hyperthyroidism).
*Papillary carcinoma*
- **Papillary thyroid carcinoma** is the most common type of thyroid cancer and typically presents as a **painless thyroid nodule**.
- However, it is **not associated** with a strong family history of early-onset thyroid disease, episodic symptoms suggesting **pheochromocytoma**, or **Marfanoid habitus**, unlike medullary carcinoma in MEN 2B.
*Anaplastic carcinoma*
- **Anaplastic thyroid carcinoma** is a highly aggressive cancer, usually presenting in **older individuals (>60 years old)** with a **rapidly enlarging, painful neck mass** and symptoms of local **compression** (dyspnea, dysphagia, hoarseness).
- The patient's **young age** (25 years) and the **non-aggressive nature** of the mass (stable size over weeks) make anaplastic carcinoma highly unlikely.
Question 27: A 65-year-old African-American man presents to your office with dysphagia. He reports that he has found it progressively more difficult to swallow food over the past year. At the time of presentation, he is able to eat only soup. Social history is significant for asbestos exposure, multiple daily drinks of hard alcohol, and a 70 pack-year smoking history. What would you most expect to see on an esophageal biopsy of this patient?
A. Esophageal varices
B. Ferruginous bodies
C. Keratin nests and pearls (Correct Answer)
D. Glandular metaplasia
E. Mucosal abrasions
Explanation: ***Keratin nests and pearls***
- This patient's significant **smoking history** and **alcohol consumption** are major risk factors for **esophageal squamous cell carcinoma**, which is characterized microscopically by **keratin nests and pearls** on biopsy.
- The progressive **dysphagia** (difficulty swallowing) over a year, especially progressing to difficulty with solids, is a classic symptom of **esophageal cancer**.
*Esophageal varices*
- Esophageal varices are typically caused by **portal hypertension**, most commonly due to cirrhosis from chronic alcohol abuse.
- While alcohol abuse is present, varices would present with **hematemesis** or melena due to rupture, not progressive dysphagia as the primary symptom.
*Ferruginous bodies*
- These are indicative of **asbestos exposure** in the lungs, typically seen in conditions like asbestosis or mesothelioma.
- They are found in the **lungs**, not in the esophagus, although asbestos exposure is noted in the history.
*Glandular metaplasia*
- **Glandular metaplasia** of the esophagus, also known as **Barrett's esophagus**, is a precursor to **esophageal adenocarcinoma**.
- This typically results from chronic **gastroesophageal reflux disease (GERD)** symptoms, which are not mentioned in this patient.
*Mucosal abrasions*
- Mucosal abrasions would suggest trauma or inflammation but would not explain the **progressive, obstructive dysphagia** over a year.
- Abrasions are generally acute findings and not consistent with the underlying pathology suggested by this patient's long history and risk factors.
Question 28: An 8-year-old girl is brought to the clinic by her parents for fever and easy bruising. Her parents report that the child has been bruising easily ever since an upper respiratory infection 3 months ago. For example, a bump into the table resulted in a large bruise on the side of her hip for a week. Three days ago, her mother noticed that the child felt warm and subsequently measured a temperature of 101.8°F (38.8°C) that did not respond to acetaminophen. The patient denies any chills, cough, rhinorrhea, pharyngitis, sick contacts, headache, or urinary symptoms. A physical examination demonstrates a nontender, firm, and rubbery node along her left neck and splenomegaly. Laboratory findings are shown below:
Leukocyte count and differential:
Leukocyte count: 19,000/mm³
Neutrophils: 39%
Bands: 12%
Eosinophils: 2%
Basophils: 0.5%
Lymphocytes: 40%
Monocytes: 6.5%
Hemoglobin: 9.7 g/dL
Platelet count: 100,000/mm³
Mean corpuscular hemoglobin concentration: 30%
Mean corpuscular volume: 76 μm³
Reticulocyte count: 0.7%
What cytogenetic abnormality would be most likely in this patient?
A. t(9;22) - Philadelphia chromosome (BCR-ABL)
B. t(8;14) - MYC translocation
C. t(12;21) - TEL-AML1 translocation (Correct Answer)
D. t(15;17) - PML-RARA translocation
E. t(4;11) - MLL rearrangement
Explanation: ***t(12;21) - TEL-AML1 translocation***
- This is the **most common cytogenetic abnormality** in pediatric B-cell acute lymphoblastic leukemia (B-ALL), occurring in approximately **25% of cases**.
- The clinical presentation of an **8-year-old child** with fever, easy bruising, pancytopenia (anemia, thrombocytopenia), lymphadenopathy, and splenomegaly is **classic for B-ALL**.
- TEL-AML1 translocation is associated with a **favorable prognosis** and is most common in children aged **2-10 years**.
- The laboratory findings show leukocytosis with lymphocytosis, anemia, and thrombocytopenia—typical of acute leukemia with bone marrow infiltration.
*t(9;22) - Philadelphia chromosome (BCR-ABL)*
- The Philadelphia chromosome occurs in only **3-5% of pediatric ALL cases** but is more common in adults (~25%).
- While it can present with similar clinical features, it is associated with a **poor prognosis** and is much less common in this age group.
- This translocation is a high-risk feature that often requires more aggressive therapy including tyrosine kinase inhibitors.
*t(8;14) - MYC translocation*
- This translocation is characteristic of **Burkitt lymphoma**, not B-ALL.
- Burkitt lymphoma typically presents with **rapidly growing masses** (often jaw or abdominal masses) rather than the pancytopenia and systemic symptoms seen in this patient.
- The clinical presentation does not fit Burkitt lymphoma.
*t(15;17) - PML-RARA translocation*
- This translocation is **pathognomonic for acute promyelocytic leukemia (APL)**, a subtype of acute myeloid leukemia (AML).
- APL typically presents with severe coagulopathy and DIC, not the lymphoid features seen in this case.
- The patient's age and presentation are not consistent with APL, which is more common in adults.
*t(4;11) - MLL rearrangement*
- MLL rearrangements are associated with **infant ALL** (particularly in children <1 year old) and confer a **poor prognosis**.
- While possible in older children, this is much less common than t(12;21) in the **8-year-old age group**.
- MLL-rearranged ALL often presents with hyperleukocytosis and CNS involvement.
Question 29: A 19-year-old man comes to the physician because of a 2-day history of blood-speckled stools and a protruding rectal mass. He has no abdominal pain, altered bowel habits, or fever. His mother has inflammatory bowel disease. His vital signs are within normal limits. Examination shows multiple, small, hyperpigmented maculae on the lips, buccal mucosa, palms, and soles. The abdomen is soft with no organomegaly. Rectal examination shows a 4-cm pedunculated polyp with superficial excoriations on the mucosa. A colonoscopy shows 14 polyps. A biopsy shows hamartomatous mucosal polyps. This patient's diagnosis is most likely?
A. Crohn's disease
B. Juvenile polyposis syndrome
C. Ulcerative colitis
D. Familial adenomatous polyposis
E. Peutz-Jeghers syndrome (Correct Answer)
Explanation: ***Peutz-Jeghers syndrome***
- The presence of **multiple hamartomatous polyps** in the gastrointestinal tract, coupled with **hyperpigmented macules** on the lips, buccal mucosa, palms, and soles, is pathognomonic for Peutz-Jeghers syndrome.
- This condition carries an increased risk of various cancers, including colorectal, breast, gastric, and pancreatic cancers.
*Crohn's disease*
- While Crohn's disease can cause bloody stools and rectal involvement, it is characterized by **chronic inflammation**, often with **skip lesions** and **granulomas**, and does not present with mucocutaneous hyperpigmented macules or hamartomatous polyps.
- Symptoms typically include abdominal pain, diarrhea, and weight loss, which are absent here.
*Juvenile polyposis syndrome*
- This syndrome is characterized by **multiple juvenile polyps**, primarily in the colon, but it does **not involve the characteristic mucocutaneous hyperpigmentation** seen in Peutz-Jeghers syndrome.
- The polyps are typically inflammatory rather than purely hamartomatous in the same way as Peutz-Jeghers.
*Familial adenomatous polyposis*
- This condition is characterized by hundreds to thousands of **adenomatous polyps** in the colon and rectum, with a very high risk of colorectal cancer.
- It does **not typically involve hamartomatous polyps** or the mucocutaneous pigmented lesions seen in this patient.
*Ulcerative colitis*
- Ulcerative colitis is characterized by **continuous inflammation** of the colon and rectum, typically causing bloody diarrhea, abdominal pain, and tenesmus.
- It is an inflammatory bowel disease and does **not involve the presence of hamartomatous polyps** or mucocutaneous hyperpigmentation.
Question 30: A 42-year-old woman is seen by her primary care physician for her annual checkup. She has no current concerns and says that she has been healthy over the last year except for a bout of the flu in December. She has no significant past medical history and is not currently taking any medications. She has smoked 1 pack per day since she was 21 and drinks socially with her friends. Her family history is significant for prostate cancer in her dad when he was 51 years of age and ovarian cancer in her paternal aunt when she was 41 years of age. Physical exam reveals a firm, immobile, painless lump in the upper outer quadrant of her left breast as well as 2 smaller nodules in the lower quadrants of her right breast. Biopsy of these lesions shows small, atypical, glandular, duct-like cells with stellate morphology. Which of the following pathways is most likely abnormal in this patient?
A. Nucleotide excision repair
B. Base excision repair
C. Non-homologous end joining
D. Mismatch repair
E. Homologous recombination (Correct Answer)
Explanation: ***Homologous recombination***
- The patient's presentation with **multiple, bilateral breast lumps** and a strong family history of **early-onset breast, ovarian, and prostate cancers** suggests a hereditary cancer syndrome, most notably related to **BRCA1/2 mutations**.
- **BRCA1 and BRCA2 genes** are crucial for **homologous recombination**, a major pathway for repairing **double-strand DNA breaks**. Defects in this pathway lead to genomic instability and increased cancer risk.
*Nucleotide excision repair*
- This pathway primarily repairs bulky DNA adducts, such as **pyrimidine dimers** caused by UV radiation, and maintains DNA integrity by excising the damaged segment.
- Deficiencies in nucleotide excision repair are associated with diseases like **xeroderma pigmentosum**, which is characterized by extreme sensitivity to sunlight and skin cancers, not the pattern seen in this patient.
*Base excision repair*
- **Base excision repair** is responsible for repairing small, non-bulky DNA lesions, such as **oxidized or deaminated bases**, by removing the damaged base and replacing it.
- While essential for DNA integrity, its malfunction is not typically linked to the **hereditary breast and ovarian cancer syndrome** suggested by the patient's family history and clinical presentation.
*Non-homologous end joining*
- **Non-homologous end joining (NHEJ)** is an error-prone pathway for repairing **double-strand DNA breaks** by directly ligating the broken ends without a homologous template.
- While critical for DNA repair, defects in NHEJ are not the primary cause of hereditary breast and ovarian cancer, which is more specifically linked to the **BRCA1/2 genes** and the homologous recombination pathway.
*Mismatch repair*
- **Mismatch repair (MMR)** corrects errors that occur during DNA replication, such as mismatched bases or small insertions/deletions.
- Deficiencies in MMR lead to **microsatellite instability** and are characteristic of **Lynch syndrome (hereditary nonpolyposis colorectal cancer)**, which primarily increases the risk of colorectal, endometrial, and other specific cancers, but not the pattern of breast, ovarian, and prostate cancers seen here.