Diagnostic Snapshot: Aggressive Malignancy or Benign Lesion?

A Dermatofibroma B Merkel cell carcinoma C Epidermoid cyst History Mrs. B. is a 67-year-old Caucasian female. She is married, works as a housewife, and has two grown children. She denies alcohol or tobacco use. Her medical history includes hy-pertension and poorly controlled insulin dependent type 2 diabetes mel-litus. She reports a history of frequent sunbathing from her early teens until she was in her late 40s. Her surgical history is remarkable for a hysterectomy due to advanced endometrio-sis. Mrs. B. does not recall whether her ovaries were removed, but she states that she has never taken hormone replacement therapy. Her der-matologic history is remarkable for a superficial solid-infiltrating basal cell carcinoma of the upper mid-back in 2000, metatypical type 2 basal cell carcinoma of the left lower medial leg in 2008, squamous cell carcinoma of the wrist in 2011, and several other precancerous lesions that were treated both topically and cryogenically. Mrs. B. presents today with a chief complaint of a red nodule located on her lower leg that has been present for approximately 6 months. She states that it is not painful and that it does not itch or bleed. She first noticed the nodule while vacation-ing at the beach. At that time, she thought it was perhaps an infected hair from shaving but says that it has not bothered her at all. She comes in today, however, because she is concerned that the nodule appears to have tripled in size seemingly " overnight. " She recalls a family member with melanoma dying many years ago. Since that time, she has always been particularly concerned about getting the same type of cancer. She denies any type of trauma and is not aware of having been exposed to insects or spiders that could have bitten her. She presents with no other complaints at this time. Upon physical examination, Mrs. B.'s left lower medial leg reveals a firm, 2.2-cm, violet-red, dome-shaped, solitary nodule surrounded by several tan-colored macules that are consistent with those frequently seen on the skin of patients of advanced age (see Figure above). The nodule is well circum-scribed and has a shiny, smooth surface. No scaling, oozing, or bleeding is visualized. No fluctuance or tenderness is noted. There are several small dry papules bilaterally, consistent with actinic keratoses. Foot exam is normal, with no ulcerations observed. The remainder of the exam is unremarkable. Workup Mrs. B.'s preliminary …