ABSTRACT
This chapter describes the histopathology and differential diagnosis of the metastases of the digital tip. Sometimes, metastases to the nail region may be the first manifestation of an internal malignancy. The clinical appearance of these metastases varies considerably. A metastatic hypopharynx carcinoma imitated necrotizing vasculitis and ulcerating subungual metastases of lung squamous cell carcinoma looked like vasculitic nodules. Acrometastases were observed after the use of frozen gloves during adjuvant chemotherapy of breast carcinoma. Lung, kidney, and breast carcinoma are the most frequent causes of acrometastases. Approximately 20" of these acrometastases are found in the distal phalanx. In general, very few subungual metastases allow their origin to be determined with certainty except for clear-cell renal carcinoma and melanoma that can usually be diagnosed. Some group antigens may be able to limit the number of malignancy potentially responsible for the metastasis, such as keratins, vimentin, neural antigens, lymphocyte markers, carcinoembryonic antigen, specific enzymes and hormones.
