MCC, is an uncommon tumor, which mostly occurs as an asymptomatic, solitary, firm and red-pink nodule. It has been linked to increased sun exposure [1], both in its anatomic and geographical distribution. Usually is nonulcerated and ranges from 0.8 to 4 cm in diameter [2, 3].
Predominantly involves the head and neck region (65%) [4, 5], followed by the upper extremities (18%), and the lower extremities (13%) [3]. The precice origin is still controversial. However, the Merkel cell (assumed to be a touch receptor) and the melanocyte are the cutaneous counterparts of the Amine Precurcor Uptake and Decarboxylation (APUD) cells, which are of neuroectodermal origin [6, 7].
The tumor is composed of small blue cells with hyperchromatic nuclei and minimal cytoplasm. Mitoses, nuclear fragments and lymphovascular invasion are almost invariable features [8]. Immunoistochemistry for cytokeratin species more typical of simple epitelial cells than keratinocytes, permits a differential identification of Merkel cells in tissue sections [9]. The immunoistochemical profile is characterized of positivity for Neuron-Specific Enolase (NSE), Neurofilament Protein (NFP) and CD57- CD99 [10]. A single punctate zone of cytoplasmic immunoreactivity for cytokeratins especially CK20 is more characteristic [11]. The reaction for CK20 has been used as a finding against metastatic small cell carcinoma of the lung (Cytokeratin 7+ and Thyroid Transcription Factor 1+), small cell melanoma (S100+) and lymphoma (Leucocyte Common Antigen +) [12].
MCC appears to metastasize principally via the lymphatics in a predictable stepwise fashion, with an initial involvement of the regional lymph nodes and subsequent systemic spread [13]. If the lymph nodes are not palpable, the pathological examination of the primary tumor (larger than 2 cm, high mitotic rate and lymphatic invasion) serves as a parameter for the need of lymph node biopsies [5]. Surgical excision with tumor free margins is the primary therapy for stage I-localized disease, with a 64% of survival in 5 years. However recent studies have shown that there is no clear evidence of a difference in survival [2, 14], when the margins of resection are less than the 2–3 cm as generally recommended [2, 13]
In fact, Mohs micrographic surgery may be more efficacious than wide excision as it inspects all major borders, including the deep margin (MCC often shows extensive vertical growth) and also allows maximal sparing of normal additional tissue, especially in such cosmetically sensitive anatomic areas as the face [15]. A useful adjunct in the treatment of MCC is the sentinel node mapping, which identifies the status of the first draining lymph node and allows to avoid unnecessary lymphadenectomies and the resulting postoperative morbidity [16].
MCC cells are radiosensitive, and several studies have argued for the benefits of radiation therapy not only after resection for local recurrence and palliation but as well as adjuvant treatment after initial surgery with curative intent [12]. Chemotherapy is the least studied theraupetic component and propably is mandatory in unresectable or unmanagable by radiotherapy tumors, as well as in metastatic disease [8, 17].
CLL occurs primarily in middle-aged and elderly individuals, with increasing frequency in successive decades of life. It involves slow proliferation and accumulation of incompetent B-lymphocytes and concurrent abnormalities in both humoral and cellular immunity. The majority of patients live 5–10 years, with an initial course that is relatively benign but followed by a terminal, progressive and resistant fase lasting 1–2 years. During the later phase, morbidity is considerable both from the disease and the associated incidence of malignant neoplasms (especially skin cancers as squamous cell carcinoma, Kaposi sarcoma and melanoma) [19]. CLL shares a clinical and morphological overlap with Small Lymphocytic Lymphoma (SLL). In fact if a patient has an absolute lymphocytosis of > 5000/mm3 in the peripheral blood, CLL is diagnosed, regardless of the findings in the lymph node [19].
Treatment of CCL ranges from periodic observation with treatment of infectious, hemorrhagic or immunologic complications to a variety of therapeutic options, including steroids, alkylating agents, purine analogues, combination chemotherapy, monoclonal antibodies and transplant options [20]. As it occurs in an elderly population, progresses slowly and generally is not curable, it is usually treated in a conservative fashion [21]. Involved-field radiation therapy with relatively low doses of radiation can effect an excellent response for both CLL and Small Lymphocytic Lymphoma, especially when the lymphoma cells are contained in one or two areas of lymph nodes in the same part of the body.
