(BMJ)—A 70-year-old woman presented with an 8-week hx of a lesion on the dorsum of her R hand. She had multiple recent trips to Australia. The lesion had failed to respond to 2 prior rounds of cryocautery. PMHx: lymphoma diagnosed 15 years prior, last tx finished 7 years prior; no warts. Exam: 2-cm red, firm lesion with protruding horn. Excisional bx confirmed the dx. What is it?
Seborrheic keratosis
HPV wart
Invasive squamous cell cancer
Keratoacanthoma
Actinic keratosis
You are correct. Bx confirmed invasive squamous cell cancer. This patient had several risk factors: age, sun exposure, past lymphoma, past chemo, and no hx of warts. Other invasive features of squamous cell cancer relevant to this case include the lesion’s arrival over 8 weeks and its wide, thick, red base with a diameter larger than the height of the horn. About 35% of keratotic horns are invasive squamous cell cancers. This patient had cancerous cells evident in the deep margin; therefore, she underwent further surgery. Second operative histology revealed no residual cancer.

BMJ 2019;364:l595