The previously discussed cutaneous neoplasms seen in solid organ transplant recipients are not only common in the setting of chronic immunosuppression, but also are relatively common in the nontransplant population. Therefore, population-based studies of incidence and prevalence of these tumors associated with long-term antirejection regimens reveal statistically significant trends that are clinically meaningful in the care of transplant patients. In contrast, large, controlled, statistically significant studies of rare cutaneous neoplasms in both immunocompetent and organ transplant patients are lacking. Rare cutaneous neoplasms are, as the term implies, infrequent observations in immunocompromised as well as immunocompetent hosts. The literature pertaining to these rare tumors is characterized primarily by case reports and summaries of case reports. Table 30.1 lists the rare cutaneous neoplasms that have been reported in transplant recipients, as well as their corresponding biological behavior. Because of their rarity, the relationship between these tumors and the chronic immune suppression of transplantation is tenuous, at best. However, this group of neoplasms is mentioned here both for completeness, as well as the fact that these tumors represent important considerations in the clinical and histologic differential diagnosis of some of the more common neoplasms discussed in this text.

ATYPICAL FIBROXANTHOMA

Atypical fibroxanthoma (AFX) is a tumor of presumed mesenchymal origin that presents as a rapidly growing, sometimes ulcerated nodule on actinically damaged skin of the head and neck region of older individuals (Figure 30.1). AFX is a low-grade malignancy associated with rare reports of metastases to local lymph nodes.