Carcinoid call-point gGmbH

1. General

1.1 Definition:

The cutaneous neuroendocrine carcinoma was first described under the term "trabecular carcinoma" [Toker 1972] and is often referred to as "Merkel cell carcinoma. Most authors suggest that the Merkel cell in the skin, which transmits the sensation of touch is apparent in dermal nerve endings, [Minor 1994]. The Merkel cell is assigned to the APUD system (Amine Precursor Uptake and Decarboxylation) system, which also includes effective neuroendocrine cells of the gastrointestinal and bronchial tract. The Merkel cell expressing both of Merkel Cell Carcinoma both epithelial and neuroendocrine markers. The diagnosis can usually be histologically / immunohistochemically secured.

1.2 Clinic and histology:

The Merkel cell carcinoma usually presents as a solid, reddish-purple, dome-shaped or globular, and sometimes tumor dar. plaque ulceration may occur secondarily. Most tumors have a diameter of less than 2 cm. Typically, the tumors seen in sun-exposed areas of the face or extremities. Only about 10% of Merkel cell carcinomas occur on the trunk.

Histologically, the Merkel cell carcinoma located a dermal tumor, which down to the subcutaneous fat tissue, can often extend into the muscles. It consists of small epithelioid cells, which form different sized strands and solid cell complexes with a characteristic trabecular pattern. The tumor cells are monomorphic, have a round or oval nucleus, showing few mitoses and single-cell. A typical feature of Merkel cell carcinoma is the nuclear chromatin pattern [Leong et al. 1986].

The diagnosis must be backed up immunohistochemically. As normal, non-malignant changes in Merkel cell carcinoma Merkel cells express both epithelial and neuroendocrine antigens.Valuable in the immunohistochemical diagnosis are the antibodies against cytokeratin 8, 18, 19 and 20 and antibodies against the neuron-specific enolase. Variable is the expression of chromogranin A, S-100 positivity has been variously described. Are consistently negative and vimentin, common leukocyte antigen. The antigen expression may occur when the small cell undifferentiated type of Merkel cell carcinoma is largely wasted [Leong et al 1986, Sibley et al Go 1985].

1.3 Prognosis and Staging:

Approximately 30% of patients with Merkel cell carcinoma is a lethal outcome to be expected. About half of all cancer patients is usually within the first year after removal of the primary tumor at a local relapse and / or lymph node metastasis. Retrospective studies involving more than 400 articles published in the literature, patients showed the following adverse prognostic factors: advanced stage (locoregional metastases or distant metastases), male gender, the primary tumor in the head and neck region or trunk; younger age (<60 years ).

Prognostic value also has the distinction of three histological types: the trabecular type, the intermediate type of cell and small cell type. The trabecular type is the bestdifferenzierte, while the small cell type is the least differentiated.

Table 1: Prognostic significance of histological subtypes

A generally established staging for Merkel cell carcinoma does not exist. Due to the nonneutral biological behavior in comparison to squamous cell carcinoma of the skin to take over the staging for epithelial skin tumors does not seem sensible. In the literature, the division is mostly used in Table 2 [Yarrow 1996, Hauschild et al. 1997].

Table 2: Staging of Merkel cell carcinoma

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