Primary Cutaneous Neuroendocrine Carcinoma: Case with an Atypical Location

Abstract

We present the case of a 60-year-old male with a primary cutaneous NET located in the sacro-coxigenic region without evidence of any distant disease at time of diagnosis. The diagnostic confirmation was based on immunohistochemical determination of Neuron-Specific Enolase (NSE) and Chromogranin A (Cg A). We surgically respected the tumor and because the resection margins were close, we also administered adjuvant radiotherapy. ConclusionNETs are rare, slow-growing tumors which usually have a good prognosis. Surgery with curative intent is the gold standard treatment, and this may or may be associated with adjuvant radiotherapy when adverse factors are presents or when the tumor is considered unrespectable. IntroductionPrimary cutaneous Neuroendocrine Tumor (NETs) is a very rare [1,2] with an approximate global incidence of 5.25 in 100,000 cases [3]: only ten cases have previously been reported in the literature [4][5][6][7][8][9][10][11][12][13]. These neoformations can vary enormously, both in their biological and clinical behavior, in terms of their which location, degree of differentiation and secretory activity [14,15]. Despite this, most are low-grade neoplasms with an indolent course.They are also called "carcinoid tumors" (well-differentiated neuroendocrine tumors) because they are characterized by the presence of neurosecretory granules which express specific markers, including Neuron-Specific Enolase (NSE), synaptophysin and Chromogranin A (Cg A) and CD56. In some cases, tumor cells secrete serotonin and other vasoactive substances which produce a carcinoid syndrome characterized by: abdominal pain, skin redness, diarrhea, sweating, palpitations etc [16].NETs are derived from neural crest neuroendocrine cells called Kulchitsky cells and give rise to tumors with very different degrees of differentiation, varying from carcinoid tumors to the undifferentiated small cell (oat-cell) carcinomas. They are formed by epithelial cells which exhibit neuroendocrine differentiation and can present in any anatomical location, although they usually appear in the face and trunk. Their etiology is unknown and there is no known association with sun exposure, immunodepression or other predisposing factors.The main diagnostic complexity in these cases lies in the distinction between primary cutaneous tumors and visceral neoplastic metastases because the latter may have a gastrointestinal or pulmonary origin but then cause cutaneous involvement. The mean age of presentation is between the sixth and ninth decade of life (mean 66.3 years) and studies have shown that the inicidence is similar between both sexes.We recently treated a patient with a primary cutaneous neuroendocrine carcinoma, a different entity to Merkel-Cell Carcinoma (MCC) whose primary location was the sacro-coxygeal región. Metastases in the right lateral costal area and nasal pyramid also subsequently emerged. Given the infrequency of these tumor types and the atypical location and behavior of this instance, here we describe our clinical experience of the ca...