A hyperkeratotic, erythematous crusted plaque with areas of ulceration in a solid organ transplant patient is most likely which diagnosis?

• A. Basal cell carcinoma
• B. Squamous cell carcinoma
• C. Melanoma
• D. Actinic keratosis

Answer: (B)

In solid organ transplant patients on lifelong immunosuppression, keratinocyte cancers—especially squamous cell carcinoma—are much more common and tend to be more aggressive. A lesion described as hyperkeratotic, erythematous, crusted, and with ulceration fits invasive squamous cell carcinoma well. The thick hyperkeratosis reflects abnormal squamous cell proliferation producing excess keratin, while ulceration indicates invasion through the epidermis into the dermis and tissue breakdown. Immunosuppression blunts immune surveillance, allowing these lesions to develop and progress more readily.

Basal cell carcinoma usually appears as a pearly, translucent papule with telangiectasias and rolled borders, and ulceration, if present, is not the defining feature. Melanoma typically shows a pigmented lesion with asymmetry, irregular borders, and color variation rather than a predominantly crusted, hyperkeratotic plaque. Actinic keratosis is a rough, scaly patch on sun-exposed skin and is considered a precursor lesion rather than an invasive cancer, though it can progress to squamous cell carcinoma.

Thus, the description most strongly points to squamous cell carcinoma.