Multiple neuroendocrine carcinomas (so-called Merkel cell tumours) of the skin. Report on two cases with unique clinical course

The Merkel cell and associated neoplasms in the eyelids and periocular region

Merkel cells are clear oval cells in the epidermis and outer root sheaths of hair follicles, which are probably of epithelial origin, share ultrastructural features with neuroendocrine cells, and are found in association with touch receptors. In the eyelid, they occur singly in the epidermis and external root sheaths of hairs and eyelashes, and in specialized touch spots alternating with eyelashes. Their typical electron microscopical and antigenic features include dense-core granules, intranuclear rodlets, spinous processes, and a positive reaction for specific cytokeratins, epithelial membrane antigen, neuron-specific enolase, chromogranin and synaptophysin. Merkel cell carcinoma probably develops from precursor cells which give rise to keratinocytes and Merkel cells, and nearly one out of ten Merkel cell carcinomas occur in the eyelid and periocular region. They tend to be bulging lesions near the lid margin of elderly patients, reddish in color, and erythematous with telangiectatic vessels. The diagnosis is based on the frequent presence of neurofilaments and paranuclear aggregates of intermediate filaments in addition to features typical of normal Merkel cells. The tumor often mimics lymphoma or undifferentiated carcinoma and frequently invades lymphatic vessels. One third of Merkel cell carcinomas recur, almost two thirds give rise to regional node metastases, and up to one half metastasize widely and result in death. Initial treatment should be prompt and aggressive, with wide resection and routine postoperative irradiation. Although metastatic lesions often respond to radiation therapy and cytostatic drugs, these treatments are mainly of palliative value.

Involvement of chromosome 22 in a Merkel cell carcinoma in a patient with a previous meningioma

The relatively simple cytogenetic findings in an aggressive metastatic Merkel cell carcinoma are reported. Deletion 2p was found in 100% of the cells. Nevertheless, this was considered a secondary (metastatic?) change because the same aberration has been found in several other kinds of malignancy. The involvement of chromosome 22 [del(22q) and -22] in 85% of the cells seemed more intriguing, considering the fact that the Merkel cell carcinoma followed a previous meningioma.

[Clinical aspects and therapy of Merkel cell tumor--report of 4 personal cases and review of the literature]

Four cases of Merkel cell tumor located in the face or on the trunk are presented. In a literature review 339 cases were found and analysed. The Merkel cell tumor is a neuroendocrine tumor of the skin derived from the Merkel cells. It is located most often in the face and neck area. Typically, it is an exophytic node, has a red-blue color and measures 25 mm in diameter on the average. Since it is metastasizing it is a malignant tumor. Regional node metastases were found in 27%, local recurrences occur in 51%, and distant metastases were seen in 32% of the cases. The best therapy is excision with wide margins as is the rule for a malignant skin tumor. While the tumor reacts to radiotherapy, chemotherapy seems to be of no help.

Primary small cell carcinoma of skin. Histogenetical study

Four cases of primary small cell carcinoma of the skin (PSCCS) are presented (ages ranging from 60 to 68 years). Ultrastructurally, two cell types were identified, with both presenting electron-dense secretory granules and paranuclear intermediate filaments. Argyrophylia was positive in one case. Intense solar elastosis in two cases and actinic keratosis in one case suggest a possible role from solar damage in the pathogenesis of this tumor. According to comparative ultrastructural features, different histogenetic possibilities in Merkel cells (MC), peripheral neuroblastic tissue, and totipotential cells are discussed. Some neurosecretory-like granules were observed in basal cell carcinoma (BCC). We consider that PSCCS reproduces cells similar to MC and probably originates in stem cells with totipotential capacity.