This lesion on the scalp of a 78-year-old man was clinically thought to be a squamous cell carcinoma. Syringocystadenoma papilliferum is a rare lesion, often found on the scalp, but can occur more rarely at other sites. They are often associated with a nevus, such as nevus sebaceus. Although these lesions may be flat, it is not uncommon for them to have a warty appearance, as in this case. Usually, one will find continuity of the cyst with the overlying epidermis, although this was not found in our case. They behave in a benign fashion.
At higher power view of the cystic spaces in the same lesion, one can appreciate the densely packed lymphocytes and plasma cells within the papillary projections. The lining consists of an apparent two layers of flattened-to-cuboidal cells. Focal decapitation secretion is present.