Surgical Pathology Flashcards

A 45-year-old man presents with a painless testicular mass. Serum AFP is markedly elevated but beta-hCG is normal. Which testicular tumour is most likely?

Answer: Yolk sac tumour (endodermal sinus tumour)

Yolk sac tumour (endodermal sinus tumour) characteristically produces alpha-fetoprotein (AFP). Pure seminomas do NOT produce AFP (any AFP elevation in a seminoma indicates a non-seminomatous component). Choriocarcinoma produces beta-hCG. Mature teratomas in adults do not typically elevate tumour markers but may have mildly raised AFP.

A colonic polyp is classified as a villous adenoma with high-grade dysplasia. What is the approximate risk of malignant transformation compared to a tubular adenoma?

Answer: 40-50%

Villous adenomas carry the highest malignant potential among adenomatous polyps, with a transformation risk of approximately 40-50% (compared to 5% for tubular adenomas and 20% for tubulovillous). High-grade dysplasia further increases this risk. The adenoma-carcinoma sequence (Vogelstein model) describes the stepwise accumulation of genetic mutations (APC → KRAS → DCC → p53).

A patient with a parotid gland mass undergoes superficial parotidectomy. Histology shows a biphasic tumour with epithelial and myoepithelial components within a chondromyxoid stroma. What is the diagnosis?

Answer: Pleomorphic adenoma

Pleomorphic adenoma (mixed parotid tumour) is the most common salivary gland tumour (60-70%). It is characterised histologically by a biphasic mixture of epithelial and myoepithelial cells within a variable chondromyxoid (cartilaginous/myxoid) stroma. Despite being benign, it has a recurrence risk of 1-5% after superficial parotidectomy, and long-standing tumours carry a small risk of malignant transformation (carcinoma ex pleomorphic adenoma).

In the TNM staging of colorectal cancer, a tumour that has penetrated through the muscularis propria into the pericolorectal tissues is classified as which T stage?

Answer: T3

T3 colorectal cancer has invaded through the muscularis propria into pericolorectal (subserosa/mesorectum) tissues. T2 extends into but not through the muscularis propria. T4a penetrates the visceral peritoneum, and T4b directly invades adjacent organs/structures. T staging is a critical determinant of prognosis and adjuvant therapy decisions.

Which type of renal cell carcinoma is most common, accounting for approximately 70-80% of cases?

Answer: Clear cell carcinoma

Clear cell renal cell carcinoma is the most common subtype (70-80%), arising from proximal tubular epithelium. It is strongly associated with VHL (von Hippel-Lindau) gene inactivation on chromosome 3p, leading to upregulation of HIF and VEGF. It characteristically shows cells with clear cytoplasm due to glycogen and lipid content. It is the subtype most responsive to anti-VEGF targeted therapies.

A 30-year-old woman presents with a firm, mobile 3 cm breast lump. Excision biopsy shows a well-circumscribed lesion with a leaf-like pattern of stromal overgrowth covered by epithelium. What is the most likely diagnosis?

Answer: Phyllodes tumour

Phyllodes tumour (cystosarcoma phyllodes) shows a characteristic leaf-like (phyllodes) architecture with stromal hypercellularity projecting into epithelium-lined clefts. It is classified as benign, borderline, or malignant based on stromal cellularity, mitotic activity, and margins. Unlike fibroadenomas, phyllodes tumours have a tendency for local recurrence and require wide excision with clear margins.