Letter to the Editor
Merkel cell carcinoma: an illustrative case and review

Merkel cell carcinoma (MCC) was first described by Toker in 1972, as trabecular carcinoma [1, 2]. It is a primary cutaneous tumor of neuroendocrine origin characterized by aggressive course and poor prognosis [3–5]. Agelli and Clegg in 2007 showed that the incidence of MCC in the U.S. was 0.24/100000 per year [6]. Merkel cell carcinoma has a high propensity for local recurrence, lymphatic spread and distal metastases. Metastases are usually found in the skin (28%), liver (13%), bones (10%), and brain (6%). Typically, at the time of diagnosis, local or distant metastases are present. Merkel cell carcinoma affects mainly the elderly, more often men, usually between 65 and 85 years of age. Primary lesions are frequently localized in sun-exposed areas. In 29–40% of cases it is the head and neck region, followed by extremities (21–38%), trunk (7–23%), and other skin regions (3.4–12%) [7]. Merkel cell carcinoma often arises in the setting of immunodeficiency (post-transplant immunosuppression or HIV infection), autoimmune connective tissue diseases and neoplasm, particularly Hodgkin’s disease, B-cell lymphoma, chronic lymphocytic leukemia, breast and ovary cancer [8, 9]. Established risk factors for MCC development are UV radiation, immunosuppression and Merkel cell polyomavirus infection [7, 10].
Clinically MCC appears as an indolent, rapidly growing blue-red nodule often with telangiectasias. Histological findings are: monomorphous indistinct bluish cells, often arranged in trabeculae or strands with numerous mitotic figures, apoptotic cells and occasionally necrosis. Lymphocyte intra- and peritumoral infiltration is common.
Routine histological examination may be of limited diagnostic value. Immunohistochemical staining, particularly against cytokeratin 20 (CK20) or chromogranin A, increase the effectiveness of MCC diagnosis [11].
Therapeutic management of choice is wide surgical excision or Mohs micrographic surgery of the tumor with sentinel lymph node biopsy. Adjuvant radiotherapy or chemotherapy is administered according to the clinical staging of disease. Metastases are treated with protocols similar to small-cell lung carcinoma management [12, 13].
A 74-year-old woman presented to our clinic with blue-red colored, well-demarcated skin tumors ranging from 0.5 cm to 2.0 cm in diameter located on the left lower extremity. Lesions were hard and painful on palpation (Figure 1). The enlarged inguinal lymph nodes were present...


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