Differential Diagnosis
- Single most likely diagnosis
- Basal cell carcinoma: The patient's history of prolonged sun exposure, the presence of a well-demarcated hyperkeratotic plaque on the upper lip, and the appearance of adenoma sebaceum (which can be associated with basal cell nevus syndrome, although the primary lesions described here don't directly suggest this syndrome) make basal cell carcinoma a strong consideration. The family history of various cancers could also hint at a genetic predisposition to skin cancers.
- Other Likely diagnoses
- Squamous cell carcinoma: Given the patient's smoking history and prolonged sun exposure, squamous cell carcinoma is a plausible diagnosis. The appearance of a hyperkeratotic plaque is consistent with this type of skin cancer.
- Keratoacanthoma: This is a low-grade malignancy that can appear similar to squamous cell carcinoma and can present as a hyperkeratotic plaque. It often resolves on its own but can be difficult to distinguish from squamous cell carcinoma without biopsy.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Merkel cell carcinoma: Although less common, Merkel cell carcinoma is aggressive and has a poor prognosis if not caught early. It can present as a rapidly growing nodule, but the description given doesn't strongly suggest this diagnosis. However, its potential deadliness warrants consideration.
- Metastatic disease: Given the family history of various cancers, there's a remote possibility that the lip lesion could be a metastasis from another primary site, although this would be unusual for the described appearance and location.
- Rare diagnoses
- Basal cell nevus syndrome (Gorlin syndrome): While the presence of adenoma sebaceum might suggest this, the syndrome typically includes other findings such as jaw cysts, palmar or plantar pits, and a history of multiple basal cell carcinomas, which are not mentioned here.
- Sebaceous carcinoma: This is a rare but aggressive malignancy that could present with similar lesions, especially in the context of adenoma sebaceum, which can sometimes be associated with sebaceous neoplasms in the context of Muir-Torre syndrome (a subset of Lynch syndrome, given the family history of colon and uterine cancer).