PA33.1-4 | Skin — Graded Quiz

A 63-year-old farmer presents with a 3-year-old erythematous, scaly plaque on the dorsum of his right hand. Biopsy shows: lower epidermal layer atypia with preservation of upper layers (no full-thickness involvement), solar elastosis in the dermis, and an intact basement membrane. No dermal invasion is seen. He is concerned because his neighbour had a similar lesion that became a cancer. Which statement best explains the biological behaviour of this lesion and the risk it confers?

A pathology report on a skin excision from the right cheek of a 70-year-old man describes: 'islands and nests of atypical basaloid cells extending from the epidermis into the dermis, with peripheral nuclear palisading, artefactual retraction clefts between tumor nests and stroma, and mucin deposition within nests.' There is no keratin pearl formation. What is the diagnosis, and what is the most important clinical fact about this tumor's behaviour?

A 57-year-old woman presents with a pigmented lesion on her back showing asymmetry, irregular border, colour variegation (black, tan, red areas), and diameter 9 mm. Wide local excision is performed. The pathology report states: 'Breslow thickness 2.4 mm; Clark Level IV; radial growth phase absent; vertical growth phase present; no ulceration; 3 mitoses/mm²; sentinel lymph node positive for micrometastasis (0.4 mm deposit).' Which statement MOST accurately represents the prognostic hierarchy for this patient?

A 45-year-old woman with a history of immunosuppression following renal transplant presents with a rapidly growing, keratinising, nodular lesion on the back of her right hand. Biopsy shows well-differentiated squamous cell carcinoma with perineural invasion. Her dermatologist is concerned about high-risk features. Which combination of features in this patient confers the highest risk of nodal metastasis and locoregional recurrence?

A 38-year-old man develops a painful, firm nodule on his lower leg. On examination, pressing on the nodule with a finger causes it to dimple inward ('dimple sign'). Biopsy shows a dermal nodule of spindled fibroblast-like cells with storiform (cartwheel) arrangement, overlying epidermal hyperplasia, and a trapped peripheral fat lobule. No nuclear atypia, no necrosis, no mitotic figures. CD34 is negative; Factor XIIIa is focally positive. Which entity does this represent, and how does it differ from a dermatofibrosarcoma protuberans (DFSP) on both clinical and molecular grounds?

A 32-year-old woman has a 4 mm brown-black lesion on her right shoulder. Dermoscopy shows irregular network, asymmetric pigmentation, and a notched border. Excision biopsy is performed. Histology shows: pleomorphic melanocytes in nests at the dermal-epidermal junction with pagetoid spread (single cells throughout the epidermis), and minimal dermal invasion limited to the papillary dermis (Breslow thickness 0.35 mm). Mitoses: 0/mm². Margins clear. Sentinel node is not performed. What is the CORRECT management rationale, and which histological feature provides the most diagnostic weight for melanoma vs a dysplastic naevus?

A 29-year-old woman with BRAF V600E-positive metastatic melanoma is started on a BRAF inhibitor. Her oncologist explains that despite initial dramatic response, most patients relapse within 6–12 months. A pathologist examining biopsy from a regrown lesion finds increased expression of MEK-ERK pathway proteins. Which of the following pathological and molecular reasoning chains MOST accurately explains both (1) why BRAF V600E drives melanoma and (2) why resistance develops through MEK-ERK reactivation?

A dermatopathologist reviews a slide from a 65-year-old man's facial skin lesion. The slide shows: islands of basaloid cells, peripheral palisading of nuclei at the edge of each island, artefactual retraction spaces between islands and adjacent stroma, abundant mucin within the tumor nests, and no intercellular bridges or keratin pearls. In the same session, another slide from a 58-year-old woman's back shows: tongues of squamous cells infiltrating the dermis with abundant eosinophilic cytoplasm, central concentric keratin whorl formation ('pearl'), visible intercellular bridges (desmosomes), and a desmoplastic stroma. Which diagnostic pairing MOST accurately identifies both tumors, differentiates them histologically, and predicts their differing propensity for metastasis?

A 55-year-old man had a Clark Level II, Breslow 0.4 mm melanoma on his left shoulder excised 18 months ago with clear margins. He now presents with a painful 2 cm nodule in the left axilla. Fine needle aspiration of the axillary nodule shows large pleomorphic cells with prominent nucleoli, intracytoplasmic melanin granules, and abundant mitoses. He has no other sites of disease. Which sequence of events best explains the progression from the primary melanoma to the current axillary presentation?

A 51-year-old man presents with a 1.5 cm nodule on the medial aspect of his right thigh that has been present for 8 years. It is firm, non-tender, moves with overlying skin, and dimples inward when the skin is pinched. Biopsy shows a dermal proliferation of spindled cells in a storiform pattern, with trapped fat at the periphery, overlying epidermal hyperplasia, and no cytological atypia. Factor XIIIa is positive; CD34 is negative. He asks: 'Will this come back after removal, and could it become cancer?' What is the accurate answer?

A 48-year-old man has a 7 mm pigmented lesion removed from his upper back. Histology: junctional nests of melanocytes confined to the dermal-epidermal junction with mild nuclear enlargement and irregular spacing; scattered single melanocytes along the basal layer confined to the junctional zone (no pagetoid spread); no dermal invasion; architectural disorder present but atypia is mild. A second lesion from the same patient's forearm shows: compound naevus with intradermal nests, mononuclear melanocytes with small nuclei, 'maturation' (decreasing cell size with depth), and no mitoses. Which statement MOST accurately summarises the biological distinction between these two lesions?

A 75-year-old man with a 50-pack-year smoking history and type 2 diabetes presents with a 3 cm ulcerated tumor on his lower lip. Biopsy shows invasive SCC with perineural invasion and poorly differentiated areas. Sentinel lymph node biopsy of the ipsilateral cervical nodes is performed; the pathologist identifies a 3 mm deposit of SCC in one of four nodes examined. The multidisciplinary team is deciding on adjuvant therapy. Which pathological feature combination in this case represents the highest-risk category, and what is the primary route of lymphatic drainage from lip SCCs?