A 65-year-old man with a 40-pack-year smoking history presents with hemoptysis and a persistent cough. Chest CT shows a 3.5 cm centrally located mass in the right main bronchus. Positron emission tomography confirms a malignant nodule. Bronchoscopy with transbronchial biopsy is performed and a specimen sample of the nodule is sent for frozen section analysis. The tissue sample is most likely to show which of the following tumor types?

Metastasis of colorectal cancer

A 53-year-old farmer presents to the clinic for evaluation of a pigmented lesion on his arm. He states that he first noticed the lesion last year, but he believes that it has been slowly growing in size. He otherwise does not have any complaints and is generally healthy. Which of the following findings on physical exam would suggest a malignant diagnosis?

Different pigmentation throughout the lesion

Flat lesion with symmetric hyperpigmentation

Hyperpigmented lesion with smooth borders

A 27-year-old woman presents to her primary care physician because of headaches that she has had over the last three weeks. She has not had any significant past medical history though she does recall that various types of cancer run in her family. She has also noticed that she has been gaining some weight, and her feet no longer fit into her favorite shoes. On presentation, her temperature is 98.6°F (37°C), blood pressure is 159/92 mmHg, pulse is 75/min, and respirations are 16/min. Physical exam reveals 1+ edema in her lower extremities bilaterally. She is placed on captopril and presents to the emergency department two weeks later after a minor motor vehicle accident. She is cleared of any serious injuries, and as part of her workup, labs are drawn with the following results: BUN: 47 mg/dL Creatinine: 1.4 mg/dL Which of the following findings would most likely also be seen in this patient?

String-of-beads appearance on angiography

Atherosclerotic plaques blocking blood flow

Mass present in adrenal medulla

A 65-year-old man is admitted to the hospital because of a 1-month history of fatigue, intermittent fever, and weakness. Results from a peripheral blood smear taken during his evaluation are indicative of possible acute myeloid leukemia. Bone marrow aspiration and subsequent cytogenetic studies confirm the diagnosis. The physician sets aside an appointed time-slot and arranges a meeting in a quiet office to inform him about the diagnosis and discuss his options. He has been encouraged to bring someone along to the appointment if he wanted. He comes to your office at the appointed time with his daughter. He appears relaxed, with a full range of affect. Which of the following is the most appropriate opening statement in this situation?

What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies?

Your lab reports show that you have an acute myeloid leukemia

You must be curious and maybe even anxious about the results of your tests.

I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.

Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?

Nomenclature of neoplasms for USMLE Step 3: High-Yield Pathology Lessons

Benign vs. Malignant - Friend or Foe?

Benign Tumors (-oma): Generally localized, slow-growing, and non-invasive.
Malignant Tumors (-carcinoma, -sarcoma): Invasive, fast-growing, and have the potential to metastasize.

Benign vs. Malignant Tumor Cell Growth

Feature	Benign	Malignant
Differentiation	Well-differentiated; resembles parent tissue	Variable; can be anaplastic (undifferentiated)
Growth Rate	Slow; rare, normal mitoses	Rapid; numerous, atypical mitoses
Local Invasion	Cohesive, often encapsulated; non-invasive	Infiltrative growth; invades local tissue
Metastasis	Absent	Present; definitive sign of malignancy

⚠️ Malignant Mimics: Some "-omas" are malignant (e.g., Melanoma, Lymphoma, Seminoma).

Epithelial Neoplasms - Linings Gone Wild

Benign (-oma): Named based on cell of origin or microscopic architecture.
- Adenoma: From glands or forms glandular patterns (e.g., colonic tubular adenoma).
- Papilloma: Produces macroscopic or microscopic finger-like projections (e.g., laryngeal papilloma).
- Cystadenoma: Large, hollow cystic masses (e.g., ovarian serous cystadenoma).
Malignant (-carcinoma): Arise from epithelium of any germ layer (ectoderm, endoderm, mesoderm).
- Adenocarcinoma: Glandular growth pattern (e.g., lung, colon, prostate).
- Squamous Cell Carcinoma: Forms nests of squamous cells, often with keratin pearls (e.g., skin, esophagus, lung).
Metastatic Spread: Carcinomas characteristically spread via lymphatics first.

⭐ Carcinoma in situ (CIS): A critical non-invasive stage. Features full-thickness dysplasia of the epithelium without penetration of the basement membrane. High potential to progress to invasive carcinoma if untreated.

Mesenchymal Neoplasms - Connective Chaos

Rule: Suffix indicates behavior. Benign tumors end in -oma; malignant tumors end in -sarcoma.

Fibrous Tissue
- Benign: Fibroma
- Malignant: Fibrosarcoma
Adipose Tissue (Fat)
- Benign: Lipoma
- Malignant: Liposarcoma
Cartilage
- Benign: Chondroma
- Malignant: Chondrosarcoma
Bone
- Benign: Osteoma
- Malignant: Osteosarcoma
Blood Vessels
- Benign: Hemangioma
- Malignant: Angiosarcoma

Lipoma vs Liposarcoma Histology

⭐ Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence, often presenting in the head, neck, or genitourinary tract.

Exceptions & Oddballs - What's in a Name?

Not all "-oma" suffixes denote benign tumors. Key malignant exceptions include:
- Melanoma
- Lymphoma & Leukemia
- Mesothelioma
- Seminoma
- Hepatoma (Hepatocellular Carcinoma)
Hamartoma: A benign, focal malformation of disorganized but mature tissue native to the site of origin.
Choristoma (Ectopia): A mass of normal tissue in an abnormal location (e.g., pancreatic tissue in the stomach wall).

Hamartoma vs. Choristoma Definitions

⭐ Seminoma: A malignant germ cell tumor of the testis, it is the male counterpart to dysgerminoma in females and is notably very radiosensitive.

High‑Yield Points - ⚡ Biggest Takeaways

Benign tumors generally end in -oma (e.g., Lipoma). Malignant epithelial tumors are carcinomas; malignant mesenchymal tumors are sarcomas.

Key malignant exceptions ending in -oma include Melanoma, Lymphoma, Seminoma, and Hepatoma.

Teratomas are tumors derived from more than one germ layer.

A hamartoma is a disorganized mass of mature tissues native to the site of origin.

A choristoma is a mass of normal tissue in an ectopic location.

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