A 35-year-old woman with no significant past medical, past surgical, family or social history presents to clinic with a recently identified area of flat, intact, pigmented skin. The patient believes that this is a large freckle, and she states that it becomes darker during the summer when she is outdoors. On physical examination, you measure the lesion to be 6 mm in diameter. Which of the following is the best descriptor of this patient’s skin finding?
Q2
A 68-year-old male is brought to his primary care physician by his wife who is concerned that the patient seems more confused and irritable than usual. Three months ago, she started noticing that he appeared confused while doing simple tasks and seemed to be off balance. He has fallen several times over that time period. She has also noticed that if he is startled by one of their grandchildren, his arm starts to twitch uncontrollably. His past medical history is notable for transient ischemic attacks, hypertension, and hyperlipidemia. He takes aspirin, enalapril, hydrochlorothiazide, and rosuvastatin. He has a 30 pack-year smoking history. His family history is notable for Alzheimer’s disease in his mother and maternal uncle. His temperature is 98.6°F (37°C), blood pressure is 130/70 mmHg, pulse is 95/min, and respirations are 16/min. Physical examination reveals dysmetria and an ataxic gait. This patient’s condition is most strongly associated with which of the following findings on brain autopsy?
Q3
A 21-year-old man comes to the physician because of painful, firm, dark bumps on his neck and jawline. He has no history of serious illness and takes no medications. His brother had a similar rash. A photograph of the rash is shown. Which of the following is the most likely underlying mechanism of this patient's condition?
Q4
Two weeks after undergoing low anterior resection for rectal cancer, a 52-year-old man comes to the physician because of swelling in both feet. He has not had any fever, chills, or shortness of breath. His temperature is 36°C (96.8°F) and pulse is 88/min. Physical examination shows a normal thyroid and no jugular venous distention. Examination of the lower extremities shows bilateral non-pitting edema that extends from the feet to the lower thigh, with deep flexion creases. His skin is warm and dry, and there is no erythema or rash. Microscopic examination of the interstitial space in this patient's lower extremities would be most likely to show the presence of which of the following?
Q5
A 35-year-old nulligravid woman and her 33-year-old husband come to the physician for genetic counseling prior to conception. The husband has had severe psoriasis since adolescence that is now well-controlled under combination treatment with UV light therapy and etanercept. His father and two brothers also have this condition, and the couple wants to know how likely it is that their child will have psoriasis. The inheritance pattern of this patient's illness is most similar to which of the following conditions?
Q6
A 5-year-old girl accompanied by her mother presents to the emergency department after suffering a fall on the elementary school playground. Her mother reports that a child on the playground pushed her daughter who fell on her right side, after which she screamed and was found clutching her right leg. The girl's past medical history is significant for a fracture of the left femur and right radius over the past 2 years and an auditory deficit requiring hearing aid use starting 6 months ago. Inspection reveals a relatively short girl in moderate distress. She has brown opalescent teeth. She refuses to bear weight on her right lower extremity. Radiography of the right lower extremity reveals a femoral midshaft fracture. Which of the following is the most likely etiology of the patient's condition?
Q7
An investigator is attempting to develop a blood test to diagnose sporadic Creutzfeldt-Jakob disease (CJD). She has collected several tissue samples from adults who were diagnosed with CJD. After performing a comprehensive tissue analysis, she has identified two amino acid sequences on the affected proteins that are highly consistent across samples. She then creates antibodies that are highly specific to those amino acid sequences and is interested in using those antibodies to identify similar sequences in individuals suspected of having CJD. Which of the following tests would be most helpful in identifying these individuals?
Q8
A 48-year-old man is brought to the emergency department with a stab wound to his chest. The wound is treated in the emergency room. Three months later he develops a firm 4 x 3 cm nodular mass with intact epithelium over the site of the chest wound. On local examination, the scar is firm, non-tender, and there is no erythema. The mass is excised and microscopic examination reveals fibroblasts with plentiful collagen. Which of the following processes is most likely related to the series of events mentioned above?
Q9
A 35-year-old woman is involved in a car accident and presents with an open fracture of the left femur and severe bleeding from the left femoral artery. No past medical history or current medications. Her blood pressure is 90/60 mm Hg, pulse is 110/min, and respirations are 21/min. On physical examination, the patient is lethargic, confused, and poorly responds to commands. Peripheral pulses are 1+ in the left lower extremity below the level of the knee and 2+ elsewhere. When she arrives at the hospital, a stat hemoglobin level shows 6 g/dL. Which of the following is most correct about the patient’s condition?
Q10
A 35-year-old man is brought to the emergency room after suffering a catastrophic fall while skiing during a training session. He was found unconscious by the aeromedical emergency services team, who established an airway and cervical spine control measures. Upon arrival at the emergency department, ventilatory support is started followed by an evaluation of the patient by the neurosurgical team. His blood pressure is 210/125 mm Hg, the heart rate is 55/min, and the respiratory rate is 15/min with a Cheyne-Stokes breathing pattern. Neurological examination shows a Glasgow Coma Score of 4/15, with dilated, fixed pupils and a decerebrate posture. An MRI of the brain shows diffuse axonal injury to the brain with severe cerebral edema, multiple frontal and occipital lobe contusions and multiple flame-shaped hemorrhages in the brainstem. Despite the medical team efforts, the patient dies 24 hours later. What would be the most likely type of herniation found at this patient’s autopsy?
General Pathology US Medical PG Practice Questions and MCQs
Question 1: A 35-year-old woman with no significant past medical, past surgical, family or social history presents to clinic with a recently identified area of flat, intact, pigmented skin. The patient believes that this is a large freckle, and she states that it becomes darker during the summer when she is outdoors. On physical examination, you measure the lesion to be 6 mm in diameter. Which of the following is the best descriptor of this patient’s skin finding?
A. Wheal
B. Papule
C. Ulcer
D. Plaque
E. Macule (Correct Answer)
Explanation: ***Macule***
- A **macule** is a **flat, discolored lesion** that is less than 1 cm in diameter, which fits the description of a **flat, pigmented skin area** that is 6 mm in diameter.
- The darkening of the lesion with sun exposure is characteristic of a **freckle**, which is a type of macule caused by increased melanin production without an increase in melanocyte numbers.
*Wheal*
- A **wheal** is a **transient, elevated lesion** caused by dermal edema, typically seen in allergic reactions like hives.
- This patient's lesion is described as a **flat, pigmented area**, not an elevated, transient swelling.
*Papule*
- A **papule** is a **solid, elevated lesion** that is less than 1 cm in diameter.
- The patient's skin finding is explicitly described as **flat** and intact, not elevated.
*Ulcer*
- An **ulcer** is a **loss of epidermis and dermis**, resulting in an open sore; it is not a flat, intact pigmented lesion.
- The description of the lesion as **intact** rules out an ulcer, which involves a break in the skin surface.
*Plaque*
- A **plaque** is a **flat-topped, elevated lesion** that is larger than 1 cm in diameter.
- While flat-topped, a plaque is **elevated**, and the patient's lesion is described as **flat**, not elevated.
Question 2: A 68-year-old male is brought to his primary care physician by his wife who is concerned that the patient seems more confused and irritable than usual. Three months ago, she started noticing that he appeared confused while doing simple tasks and seemed to be off balance. He has fallen several times over that time period. She has also noticed that if he is startled by one of their grandchildren, his arm starts to twitch uncontrollably. His past medical history is notable for transient ischemic attacks, hypertension, and hyperlipidemia. He takes aspirin, enalapril, hydrochlorothiazide, and rosuvastatin. He has a 30 pack-year smoking history. His family history is notable for Alzheimer’s disease in his mother and maternal uncle. His temperature is 98.6°F (37°C), blood pressure is 130/70 mmHg, pulse is 95/min, and respirations are 16/min. Physical examination reveals dysmetria and an ataxic gait. This patient’s condition is most strongly associated with which of the following findings on brain autopsy?
A. Intracellular rounded hyperphosphorylated tau
B. Extracellular accumulation of amyloid beta
C. Multifocal ischemic changes
D. Accumulations of beta-pleated sheets (Correct Answer)
E. Intracellular aggregates of alpha-synuclein
Explanation: ***Accumulations of beta-pleated sheets***
- This patient's presentation with **rapidly progressive dementia**, confusion, ataxia, **myoclonus** (twitching arm when startled), and falls, without significant family history of early-onset Alzheimer's, strongly points towards **Creutzfeldt-Jakob disease (CJD)**.
- CJD is characterized pathologically by the accumulation of abnormally folded **prion proteins (PrPSc)**, which form **beta-pleated sheets** and cause spongiform changes in the brain.
*Intracellular rounded hyperphosphorylated tau*
- This finding is characteristic of **Alzheimer's disease (neurofibrillary tangles)**, which typically presents with a more gradual onset of memory loss and cognitive decline, rather than the rapid progression, prominent motor symptoms (ataxia, myoclonus), and falls seen in this patient.
- While there is a family history of Alzheimer's, the **rapid progression** and specific neurological signs make CJD a more likely diagnosis in this case.
*Extracellular accumulation of amyloid beta*
- This describes **amyloid plaques**, another hallmark of **Alzheimer's disease**.
- Similar to tau pathology, this finding would be more consistent with a gradual, progressive memory impairment, and less with the pronounced and rapid neurological deficits observed.
*Multifocal ischemic changes*
- While the patient has vascular risk factors (**hypertension, hyperlipidemia, TIA history, smoking**), multifocal ischemic changes (as seen in **vascular dementia**) usually lead to a stepwise cognitive decline and may cause focal neurological deficits, but typically do not present with the characteristic myoclonus and rapidly progressive ataxia seen here.
- The constellation of symptoms is more indicative of a **prion disease** than purely vascular dementia.
*Intracellular aggregates of alpha-synuclein*
- This pathology is characteristic of **Lewy body dementia** or **Parkinson's disease dementia**.
- Symptoms would include progressive cognitive decline, **fluctuating cognition**, prominent **visual hallucinations**, and parkinsonism. While some motor symptoms like falls are present, the myoclonus and rapid progression make CJD a more fitting diagnosis.
Question 3: A 21-year-old man comes to the physician because of painful, firm, dark bumps on his neck and jawline. He has no history of serious illness and takes no medications. His brother had a similar rash. A photograph of the rash is shown. Which of the following is the most likely underlying mechanism of this patient's condition?
A. Trichophyton infection of the superficial hair follicle
B. Interfollicular penetration of the skin by distal end of hair (Correct Answer)
C. Bacterial infection of the superficial or deep hair follicle
D. Follicular obstruction with subsequent duct rupture
E. Cutibacterium acnes colonization of the pilosebaceous unit
Explanation: ***Interfollicular penetration of the skin by distal end of hair***
- The description of painful, firm, dark bumps on the neck and jawline, particularly in a young man, is classic for **pseudofolliculitis barbae**, often caused by the distal end of hair penetrating the skin after shaving.
- This condition is common in individuals with **curly hair** where shaved hairs re-enter the skin, causing a foreign body inflammatory reaction.
*Trichophyton infection of the superficial hair follicle*
- This would typically present as **tinea barbae** or **tinea capitis**, characterized by scaling, erythema, and pustules, often with hair breakage, not firm dark bumps from embedded hairs.
- While fungal infections can cause folliculitis, the clinical presentation and family history of improvement with erythromycin (an antibacterial) make this less likely.
*Bacterial infection of the superficial or deep hair follicle*
- **Bacterial folliculitis** (e.g., *Staphylococcus aureus*) usually presents as pustules, papules, and sometimes carbuncles, which are typically red, inflamed, and often pus-filled.
- The family history of improvement with erythromycin might suggest a bacterial component, but the primary mechanism described (firm, dark bumps) points away from primary bacterial infection and more towards a physical cause like pseudofolliculitis barbae, which can then become secondarily infected.
*Follicular obstruction with subsequent duct rupture*
- This mechanism is characteristic of **acne vulgaris** (comedones, papules, pustules, cysts) or **hidradenitis suppurativa** (deep-seated nodules, abscesses affecting intertriginous areas), which are different in appearance and location from the described lesions.
- While related to follicular issues, the specific description of "dark bumps" and the context of shaving make embedded hairs more likely than a primary obstruction and rupture.
*Cutibacterium acnes colonization of the pilosebaceous unit*
- This is the primary bacterial contributor to **acne vulgaris**, leading to comedones, inflamed papules, and pustules, often affecting the face, chest, and back.
- Although the jawline is a common area for acne, the "firm, dark bumps" are less typical of classic acne and more consistent with ingrown hairs.
Question 4: Two weeks after undergoing low anterior resection for rectal cancer, a 52-year-old man comes to the physician because of swelling in both feet. He has not had any fever, chills, or shortness of breath. His temperature is 36°C (96.8°F) and pulse is 88/min. Physical examination shows a normal thyroid and no jugular venous distention. Examination of the lower extremities shows bilateral non-pitting edema that extends from the feet to the lower thigh, with deep flexion creases. His skin is warm and dry, and there is no erythema or rash. Microscopic examination of the interstitial space in this patient's lower extremities would be most likely to show the presence of which of the following?
A. Neutrophilic, protein-rich fluid
B. Lymphocytic, hemosiderin-rich fluid
C. Lipid-rich, protein-rich fluid (Correct Answer)
D. Protein-rich, glycosaminoglycan-rich fluid
E. Acellular, protein-poor fluid
Explanation: ***Lipid-rich, protein-rich fluid***
- The presentation of bilateral non-pitting edema extending to the thigh, with deep flexion creases, in a patient post-**low anterior resection** for rectal cancer, strongly suggests **lymphedema**.
- Lymphedema results from impaired lymphatic drainage, leading to the accumulation of **protein-rich fluid**, **macromolecules**, and **adipose tissue** in the interstitial space, which eventually becomes lipid-rich due to chronic inflammation and fibroblasts stimulating adipogenesis.
*Neutrophilic, protein-rich fluid*
- This description is characteristic of **inflammatory edema** or **purulent exudate**, typically seen in infections.
- The patient's lack of fever, chills, erythema, or warmth makes an infectious or acute inflammatory process unlikely.
*Lymphocytic, hemosiderin-rich fluid*
- **Hemosiderin deposits** are indicative of chronic **venous insufficiency** or recurrent hemorrhages, leading to red blood cell extravasation and breakdown.
- While lymphocytes can be present in chronic inflammation, the primary issue here is lymphatic obstruction, not venous stasis or bleeding.
*Protein-rich, glycosaminoglycan-rich fluid*
- While lymphedema is indeed **protein-rich**, the primary accumulation in mature lymphedema involves **adipose tissue** and fibrosis.
- **Glycosaminoglycans** accumulate significantly in conditions like **myxedema** (hypothyroidism), which was ruled out by the normal thyroid examination.
*Acellular, protein-poor fluid*
- This describes a **transudate**, typically seen in conditions like **heart failure**, **liver cirrhosis**, or **nephrotic syndrome** where there's an imbalance of hydrostatic and oncotic pressures.
- The edema in this case is **non-pitting**, suggesting a higher protein content and tissue changes characteristic of lymphatic dysfunction, not systemic fluid overload leading to protein-poor fluid.
Question 5: A 35-year-old nulligravid woman and her 33-year-old husband come to the physician for genetic counseling prior to conception. The husband has had severe psoriasis since adolescence that is now well-controlled under combination treatment with UV light therapy and etanercept. His father and two brothers also have this condition, and the couple wants to know how likely it is that their child will have psoriasis. The inheritance pattern of this patient's illness is most similar to which of the following conditions?
A. Alport syndrome
B. Schizophrenia (Correct Answer)
C. Familial hypercholesterolemia
D. Alpha thalassemia minor
E. Oculocutaneous albinism
Explanation: ***Schizophrenia***
- Psoriasis exhibits a **complex, multifactorial inheritance pattern**, influenced by multiple genes and environmental factors, similar to **schizophrenia**.
- No single gene dictates its expression, leading to variable penetrance and a risk that is higher in first-degree relatives but not Mendelian.
*Alport syndrome*
- This is an **X-linked dominant genetic disorder** primarily affecting the kidneys, ears, and eyes, characterized by a clear Mendelian inheritance pattern.
- The inheritance pattern in **Alport syndrome** is distinct and follows predictable ratios based on sex and parental genotypes.
*Familial hypercholesterolemia*
- This condition is inherited in an **autosomal dominant** manner, meaning a single copy of the mutated gene is sufficient to cause the disease, resulting in high penetrance.
- Its inheritance pattern is **monogenic** and follows a clear Mendelian 50% risk for offspring of an affected individual.
*Alpha thalassemia minor*
- This is an **autosomal recessive** condition, where affected individuals inherit two copies of the mutated gene (one from each parent).
- While it has a genetic basis, it is a **monogenic disorder** with a well-defined recessive inheritance, unlike the complex inheritance of psoriasis.
*Oculocutaneous albinism*
- This is typically an **autosomal recessive disorder** characterized by a significant reduction or absence of melanin production in the skin, hair, and eyes.
- Like alpha thalassemia minor, it is a **monogenic disorder** with a clear Mendelian recessive inheritance.
Question 6: A 5-year-old girl accompanied by her mother presents to the emergency department after suffering a fall on the elementary school playground. Her mother reports that a child on the playground pushed her daughter who fell on her right side, after which she screamed and was found clutching her right leg. The girl's past medical history is significant for a fracture of the left femur and right radius over the past 2 years and an auditory deficit requiring hearing aid use starting 6 months ago. Inspection reveals a relatively short girl in moderate distress. She has brown opalescent teeth. She refuses to bear weight on her right lower extremity. Radiography of the right lower extremity reveals a femoral midshaft fracture. Which of the following is the most likely etiology of the patient's condition?
A. Decreased cystathionine beta synthase activity
B. Vitamin D deficiency
C. Fibrillin gene defect
D. Defective type I collagen production (Correct Answer)
E. Type III collagen gene defect
Explanation: **Defective type I collagen production**
- The patient's history of **recurrent fractures** from minor trauma, **auditory deficit**, and **brown opalescent teeth** (dentinogenesis imperfecta) are classic manifestations of **osteogenesis imperfecta**, a genetic disorder characterized by **defective type I collagen production**.
- **Type I collagen** is a major component of bone, dentin, and the sclera, and its deficiency leads to brittle bones, hearing loss due to ossicle abnormalities, and dental defects.
*Decreased cystathionine beta synthase activity*
- This condition describes **homocystinuria**, which can present with skeletal abnormalities and developmental delays.
- However, typical features include **marfanoid habitus**, **lens luxation**, and **thromboembolic events**, which are not reported in this patient.
*Vitamin D deficiency*
- **Vitamin D deficiency** leads to **rickets** in children, characterized by bone pain, muscle weakness, and skeletal deformities but typically presents with **bowing of legs**, **rachitic rosary**, and **craniotabes**, not recurrent fractures from minor trauma or opalescent teeth.
- While it weakens bones, the constellation of symptoms here, especially dental and auditory deficits, points away from simple vitamin D deficiency.
*Fibrillin gene defect*
- A **fibrillin gene defect** is characteristic of **Marfan syndrome**, which presents with **long limbs**, **arachnodactyly**, **lens luxation**, and **aortic root dilation**.
- While it involves connective tissue, it does not typically cause the bone fragility and dental findings seen in this patient.
*Type III collagen gene defect*
- A **type III collagen gene defect** is associated with **Ehlers-Danlos syndrome, vascular type**, which features **easy bruising**, **fragile blood vessels**, and **organ rupture**.
- This condition leads to hypermobility and skin hyperextensibility, but not the specific combination of brittle bones, hearing loss, and dental defects seen in this patient.
Question 7: An investigator is attempting to develop a blood test to diagnose sporadic Creutzfeldt-Jakob disease (CJD). She has collected several tissue samples from adults who were diagnosed with CJD. After performing a comprehensive tissue analysis, she has identified two amino acid sequences on the affected proteins that are highly consistent across samples. She then creates antibodies that are highly specific to those amino acid sequences and is interested in using those antibodies to identify similar sequences in individuals suspected of having CJD. Which of the following tests would be most helpful in identifying these individuals?
A. Western blot (Correct Answer)
B. Northern blot
C. Southwestern blot
D. Polymerase chain reaction
E. Southern blot
Explanation: ***Western blot***
- A **Western blot** (also known as protein immunoblot) is used to detect **specific proteins** in a sample of tissue homogenate or extract.
- The scenario describes identifying **amino acid sequences** (protein markers) in affected individuals using **specific antibodies**, which is precisely the principle of a Western blot.
*Northern blot*
- A **Northern blot** is used to detect **specific RNA sequences** in a sample.
- This technique is not applicable here as the investigator is targeting **protein sequences**, not RNA.
*Southwestern blot*
- A **Southwestern blot** is used to detect and characterize **DNA-binding proteins**.
- This method is not relevant because the goal is to identify specific **protein sequences** associated with CJD, not proteins that bind to DNA.
*Polymerase chain reaction*
- **Polymerase chain reaction (PCR)** is a molecular biology technique used to **amplify specific DNA sequences**.
- While fundamental in molecular diagnostics, PCR does not directly detect **proteins** and is therefore not the appropriate assay for the described purpose.
*Southern blot*
- A **Southern blot** is a laboratory method used to detect **specific DNA sequences** in DNA samples.
- This technique focuses on DNA, whereas the investigator is looking to identify specific **protein sequences** using antibodies.
Question 8: A 48-year-old man is brought to the emergency department with a stab wound to his chest. The wound is treated in the emergency room. Three months later he develops a firm 4 x 3 cm nodular mass with intact epithelium over the site of the chest wound. On local examination, the scar is firm, non-tender, and there is no erythema. The mass is excised and microscopic examination reveals fibroblasts with plentiful collagen. Which of the following processes is most likely related to the series of events mentioned above?
A. Development of a fibrosarcoma
B. Foreign body response from suturing
C. Staphylococcal wound infection
D. Poor wound healing from diabetes mellitus
E. Keloid scar formation (Correct Answer)
Explanation: ***Keloid scar formation***
- A **keloid** is a raised, firm, nodular scar that extends beyond the original wound boundaries and is characterized by excessive collagen deposition from **fibroblasts**.
- The delayed presentation (3 months), firm nature, absence of inflammation (no erythema, non-tender), and microscopic findings of fibroblasts with plentiful collagen are classic features of a keloid.
*Development of a fibrosarcoma*
- A fibrosarcoma is a **malignant tumor** of fibroblasts, which would typically present with more aggressive growth, often pain, and possibly ulceration, none of which are described.
- While composed of fibroblasts, fibrosarcomas exhibit **cellular atypia**, mitotic activity, and invasion, which are not mentioned in the microscopic description.
*Foreign body response from suturing*
- A foreign body response usually involves a **granulomatous inflammation** around foreign material, such as suture remnants.
- The microscopic description of "fibroblasts with plentiful collagen" without mention of inflammatory cells or foreign bodies makes this less likely.
*Staphylococcal wound infection*
- A **bacterial infection** would typically present with signs of acute inflammation such as erythema, warmth, pain, and possibly pus, shortly after the wound.
- The mass is described as non-tender with no erythema, and the 3-month delay makes an active infection less probable.
*Poor wound healing from diabetes mellitus*
- Poor wound healing in diabetes often manifests as **delayed closure**, chronic ulcers, and increased susceptibility to infection, rather than an overgrowth of fibrous tissue in the form of a nodular mass.
- While diabetes can affect wound healing, the specific description of a firm, nodular mass with excessive collagen points away from typical diabetic wound complications.
Question 9: A 35-year-old woman is involved in a car accident and presents with an open fracture of the left femur and severe bleeding from the left femoral artery. No past medical history or current medications. Her blood pressure is 90/60 mm Hg, pulse is 110/min, and respirations are 21/min. On physical examination, the patient is lethargic, confused, and poorly responds to commands. Peripheral pulses are 1+ in the left lower extremity below the level of the knee and 2+ elsewhere. When she arrives at the hospital, a stat hemoglobin level shows 6 g/dL. Which of the following is most correct about the patient’s condition?
A. This patient’s laboratory findings will likely demonstrate a normocytic anemia (Correct Answer)
B. Hemoglobin concentration will be significantly decreased immediately after the acute bleeding begins
C. This patient will likely be diagnosed with iron deficiency anemia
D. Hematocrit is expected to accurately reflect the degree of blood loss immediately after acute hemorrhage
E. Her reticulocyte count is expected to be elevated at this time
Explanation: ***This patient's laboratory findings will likely demonstrate a normocytic anemia***
- In cases of **acute blood loss**, both plasma and red blood cells are lost proportionally, leading to **normocytic, normochromic anemia** as the body has not yet had time to alter red blood cell production
- The MCV (mean corpuscular volume) remains **normal (80-100 fL)** until chronic compensatory mechanisms develop
- This distinguishes acute hemorrhage from chronic blood loss, which can eventually lead to **microcytic anemia** due to iron depletion
*Hematocrit is expected to accurately reflect the degree of blood loss immediately after acute hemorrhage*
- **Immediately after acute hemorrhage**, both red blood cells and plasma are lost proportionally, so the **hematocrit initially remains relatively unchanged** despite significant blood volume loss
- The hematocrit **drops hours later** as fluid shifts from the interstitial space into the vascular compartment to restore blood volume, diluting the remaining red blood cells
- This patient's low hemoglobin at hospital arrival reflects this compensatory hemodilution process
*Hemoglobin concentration will be significantly decreased immediately after the acute bleeding begins*
- While the patient is actively bleeding, the **hemoglobin concentration may not immediately decrease** because red blood cells and plasma are lost together in proportion
- The apparent drop in hemoglobin becomes more pronounced as the body **replenishes plasma volume** through fluid shifts or after **intravenous fluid administration**, diluting the remaining red cell mass
- The hemoglobin of 6 g/dL at hospital arrival reflects fluid shifts that have already occurred
*Her reticulocyte count is expected to be elevated at this time*
- The bone marrow requires **3-5 days to mount a reticulocytosis** in response to acute blood loss and increased erythropoietin production
- At hospital arrival shortly after the accident, the **reticulocyte count will be normal** as insufficient time has passed for bone marrow response
- An elevated reticulocyte count would be expected **several days after the hemorrhage**, not acutely
*This patient will likely be diagnosed with iron deficiency anemia*
- **Iron deficiency anemia** is a **chronic condition** characterized by **microcytic, hypochromic red blood cells** due to prolonged iron loss or inadequate dietary intake
- Acute blood loss, as seen in this trauma case, causes **normocytic anemia** with normal MCV and MCH
- Iron deficiency could develop weeks to months later if iron stores become depleted without supplementation
Question 10: A 35-year-old man is brought to the emergency room after suffering a catastrophic fall while skiing during a training session. He was found unconscious by the aeromedical emergency services team, who established an airway and cervical spine control measures. Upon arrival at the emergency department, ventilatory support is started followed by an evaluation of the patient by the neurosurgical team. His blood pressure is 210/125 mm Hg, the heart rate is 55/min, and the respiratory rate is 15/min with a Cheyne-Stokes breathing pattern. Neurological examination shows a Glasgow Coma Score of 4/15, with dilated, fixed pupils and a decerebrate posture. An MRI of the brain shows diffuse axonal injury to the brain with severe cerebral edema, multiple frontal and occipital lobe contusions and multiple flame-shaped hemorrhages in the brainstem. Despite the medical team efforts, the patient dies 24 hours later. What would be the most likely type of herniation found at this patient’s autopsy?
A. Upward cerebellar herniation
B. Uncal herniation
C. Central herniation (Correct Answer)
D. Downward cerebellar herniation
E. Subfalcine herniation
Explanation: ***Central herniation***
- The presence of **Cushing's triad** (hypertension, bradycardia, irregular respirations like Cheyne-Stokes), **dilated fixed pupils**, and **decerebrate posturing** in a patient with severe diffuse cerebral edema and brainstem hemorrhages, indicates significant downward displacement of the diencephalon and midbrain through the tentorial notch.
- **Flame-shaped hemorrhages in the brainstem** (Duret hemorrhages) are a classic pathological finding associated with central or transtentorial herniation due to stretching and rupture of small perforating arteries as the brainstem is displaced.
*Upward cerebellar herniation*
- This type of herniation involves the upward displacement of the **cerebellum** and **brainstem** through the tentorial notch, often due to an infratentorial mass.
- It typically presents with **hydrocephalus**, oculomotor nerve palsies, and respiratory compromise, which are not the primary neurological signs described here.
*Uncal herniation*
- **Uncal herniation** specifically involves the medial temporal lobe (uncus) compressing the **ipsilateral oculomotor nerve (CN III)**, leading to a **dilated pupil** on one side, followed by hemiparesis.
- While a dilated pupil is present, the bilateral fixed pupils, decerebrate posturing, and diffuse brainstem involvement suggest a more widespread herniation pattern than just uncal.
*Downward cerebellar herniation*
- Also known as **tonsillar herniation**, this involves the **cerebellar tonsils** descending through the **foramen magnum**, compressing the medulla.
- This typically causes **respiratory arrest**, bradycardia, and flaccid paralysis; the clinical picture of decerebrate posturing and Duret hemorrhages points away from primary tonsillar herniation.
*Subfalcine herniation*
- **Subfalcine herniation** involves the cingulate gyrus displacing under the **falx cerebri**.
- This type of herniation often presents with **contralateral leg weakness** and can compress the anterior cerebral artery, but it does not directly cause the severe brainstem signs seen in this patient.
