DISCUSSION
Melanoma is the likely diagnosis, of course, but purpura, seborrheic keratosis, and hemangioma must also be considered among the differential diagnoses.
Purpura is a collection of extravasated RBCs that have leaked out of blood vessels which have been damaged either through trauma or other cause. Purpuric lesions will be temporary, disppearing in a matter of days as the body phagocytoses the RBC fragments.
Seborrheic keratosis is an epidermal papule or nodule with a brown-to-tan “stuck-on” look and feel, in distinct contrast with the lesion in question, which was black and intradermal.
A hemangioma is composed of blood vessels—mostly arterioles—that have formed in one location and appear lesional. Typically bright red in color and almost never black, hemangiomas occasionally require biopsy to distinguish them from melanoma.
Melanoma causes the greatest threat to the patient's life, and biopsy is crucial to ruling out this possibility or to making a definitive diagnosis. But what type of biopsy is needed? Since the vertical thickness of a melanoma determines the staging and prognosis of the lesion, incisional, full-thickness biopsy is indicated. A single punch biopsy runs the risk of providing inadequate tissue for pathologic examination, and shave biopsy would almost certainly make assessment of the vertical dimension problematic, if not impossible.
The patient's attitude about undergoing further treatment is understandable given his age. Without treatment, however, a melanoma at this site (assuming it is a melanoma) could, at the very least, cause serious local problems. Perhaps more basic to the patient's overall health, though, is the need to establish a firm diagnosis that could then serve to drive any future health decisions. My advice to the patient and his family was to consider allowing an incisional biopsy of the nodular component on the lower lid. As of this writing, they were still mulling that option. JAAPA
Joe Monroe works at the Regional Dermatology Clinic, Bartlesville, Oklahoma, and is the department editor for Dermatology Digest. He has indicated no relationships to disclose relating to the content of this article.