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PubMed1982

[The neuroendocrine Merkel cell carcinoma of the skin].

Seven primary skin tumors from 5 women and 2 men were analyzed by light and electron microscopy and immunocytochemistry. The tumors were localized on the face (3 tumors) and on the extremities. The maximum diameter was between 1 and 3.5 cm. Two tumors metastasized to the regional lymph nodes 4 months after excision of the primary, 1 tumor metastasize to the regional lymph nodes after 5 years and the patient died of multiple metastases 8 years after excision of the primary on the forearm. No local recurrences developed. The tumors occurred in the dermis with frequent infiltration of the subcutaneous tissue. The epidermis was intact. The tumor cells formed large solid clusters, while their cytoplasm was faintly basophilic and formed a small rim round the large pale nucleus. In electron microscopy many cells displayed cytoplasmic electron-dense secretory granules with a mean diameter of approx. 100 nm. Immunocytochemistry showed that a large number of cells in all tumors contained neuron specific enolase and many cells of 4 tumors yielded formaldehyde-induced fluorescence. The tumors are therefore of neuroendocrine origin and may derive from merkel cells. They frequently give rise to erroneous diagnosis of metastasis of carcinoma or malignant lymphoma to the skin.

Aged↗
PubMed1992

Epidermal Merkel cells in psoriatic lesions: immunohistochemical investigations on neuroendocrine antigen expression.

Biopsy specimens from lesional psoriatic skin and from normal controls were investigated by immunohistochemistry for the presence of epidermal Merkel cells (MC). MC were defined as epidermal cells expressing simple-type keratins, i.e. nos. 8, 18, and 19. A significant number of MC could be found at the bottom of the rete ridges of psoriatic lesions (about 19.6 MC per square mm skin surface area) and of normal skin (about 14.0 MC per square mm surface area). In contrast to normal skin, MC of psoriatic lesions were positive for synaptophysin (21.7% of simple-type keratin positive epidermal cells, i.e. MC), pancreatic polypeptide (14.8%), somatostatin (7.0%), and chromogranin A (less than 3%). The immunostaining was rather faint though significantly different from normal skin. The findings suggest that in psoriasis, epidermal MC show variations of the expression of neuropeptides compared to normal skin. Since some of the neuropeptides are thought to be involved in hyperproliferation and/or skin immunology, our findings might suggest a functional activity of epidermal MC in psoriatic lesions different from normal controls.

Antibodies, Monoclonal↗
PubMed1998

Status of cytokine and antigen presentation genes in Merkel cell carcinoma of the skin.

BACKGROUND: Merkel carcinoma (MCC) of the skin is an aggressive form of skin cancer, morphologically demonstrating both epithelial and neuroendocrine properties. However, little is known about its molecular characteristics. OBJECTIVE: The aims of the study were to explore growth characteristics and immune responses of MCCs at the molecular level. METHODS: A reverse transcription-polymerase chain reaction (RT-PCR) technique was employed to study those parameters in biopsies of MCCs and their adjacent areas. RESULTS: Analyzing mRNA levels of various epithelial genes (c-myc, cdc2 kinase, E2F, PCNA, p53, and RB, cytokeratins 5 and 10) we concluded that MCCs express markers of epithelial hyperproliferation together with markers of neuroendocrine differentiation (NSE). On the other hand, there is a lack of cytokines (IL-2, IFN-g) typical for a specific, T cell-mediated immune response in MCCs. However, several cytokines (e. g., IL-12) are produced that are required for the initial steps of that type of immune response. CONCLUSION: The epithelial hyperproliferation and impaired local immune responses might contribute to the aggressive behaviour of the tumour.

Antigen Presentation↗
PubMed1988

The role of radiotherapy in the management of primary cutaneous neuroendocrine tumors (Merkel cell or trabecular carcinoma): experience at the Peter MacCallum Cancer Institute (Melbourne, Australia).

Clinical presentation, treatment, and radiation response data are presented for 20 patients with primary cutaneous neuroendocrine tumors (Merkel cell or trabecular carcinoma). Thirty-six sites were irradiated, 26 sites were local recurrences after surgery or metastases, only 3 primary tumors were irradiated de novo. In 22 out of 23 sites (96%) a complete response of measurable tumor was observed and 1 partial response (4%), an overall response rate of 100%. Thirteen sites were irradiated prophylactically with no measurable disease present and no recurrences have been seen in these areas. There was only 1 recurrence in an irradiated site (after a low radiation dose). Forty percent (8/20) either had distant metastases at presentation (5 patients) or developed them after radiotherapy (3 patients) and five of these patients have died of metastatic disease. Follow-up time ranged from 1-77 months, and actuarial 5-year survival was 63%. In view of these findings we would advocate the wider study of primary radiotherapy after biopsy or excision biopsy for the primary lesion, and prophylactic nodal irradiation with the object of avoiding extensive surgery in these often elderly patients.

Actuarial Analysis↗
PubMed1985

Clonal heterogeneity in a case of Merkel cell carcinoma demonstrated by flow cytometry.

A 66-year-old female patient is presented in whom a rapidly growing tumour developed on the glabella. Light and electron microscopy confirmed Merkel cell carcinoma. Flow cytometry (FCM), performed of a tumour specimen, yielded multiple aneuploid stem lines. The FCM data are discussed with regard to the histological features and the biological behaviour of the tumour.

Aged↗
PubMed1983

Merkel cell tumor of the eyelid. A clinicopathologic case report.

We treated a patient who had clinical and pathological findings of a primary cutaneous tumor of the eyelid with histological and ultrastructural features of a Merkel cell carcinoma. This neoplasm is composed of cells that are thought to be derived from the neural crest and are found normally in the skin. While it may be a low-grade malignant neoplasm, this tumor can grow rapidly and metastasize. Histologically, it can mimic a metastatic undifferentiated small-cell carcinoma from the lung or other primary sites. To our knowledge, this is the first reported case involving an eyelid.

Adenocarcinoma↗
PubMed1980

A cutaneous APUDoma or Merkel cell tumor? A morphologically recognizable tumor with a biological and histological malignant aspect in contrast with its clinical behavior.

Clinical, microscopic, ultrastructural, and histochemical characteristics of a primary cutaneous tumor, identified as an APUDoma possibly arising from Merkel cells, are presented. The tumor can be diagnosed by means of routine histology. In some cases the argyrophylic staining technique can be helpful. The dermatological and histological aspects of this tumor suggest a highly malignant undifferentiated process. The biological behavior of this tumor, however seems to be of a low-grade malignancy. It is therefore important to recognize it from undifferentiated, highly malignant, mostly metastatic processes in the skin. There is also a summary of the clinical history and microscopic findings of identical tumors in 4 other patients.

Aged↗
PubMed1983

[Merkel cell tumor of the skin].

A skin tumor of a 66-year-old female was examined morphologically and immunohistochemically in relation to its histogenetic aspect. The tumor was located within the dermis and composed of compact round cells with scanty cytoplasm. Electron-microscopic study revealed the presence of dense-cored granules within the cytoplasm. Thus the tumor was thought to derive from Merkel cells. The tumor cells were positive for keratin and negative for S-100 protein by immunohistochemistry. Therefore, we posit that the tumor cells did probably not originate from the neural crest, but rather from epidermal immature cells.

Adenocarcinoma↗
PubMedDate not supplied

Neuroendocrine carcinoma of the skin (Merkel cell carcinoma): ultrastructural and immunohistochemical demonstration of neurofilaments.

In this study we characterized a skin tumor that grew in the temporal region of a 69-year-old woman. On the basis of tumor morphology, a metastasis from a small cell carcinoma of the lung was initially suggested, but X-ray and bronchoscopic studies were negative. The tumor recurred twice within a year, yet no tumors were found elsewhere in the body. Ultrastructurally, cytoplasmic organelles compatible with neuroendocrine storage granules and perinuclear aggregates of intermediate-sized (8-10 nm) filaments were found in many tumor cells. Indirect immunofluorescence microscopy revealed neurofilament-type intermediate filaments in the tumor cells but no keratin- or vimentin-type filaments. Our results further demonstrate neural properties of this tumor type, which is generally considered to have its origin from Merkel cells, the cutaneous neuroendocrine cells.

Aged↗
PubMed1984

Touch domes and Merkel cells in hamster cheek pouch epithelium.

Minute dome-shaped elevations on the epithelial surface of hamster buccal pouch were counted in full-thickness whole mounts of detached pouch epithelium. Domes were examined by light and electron microscopy. Each dome consisted of thickened epithelium containing numerous Merkel cells with associated unmyelinated terminal axons. The pouch domes have structural characteristics in common with Haarscheiben, or touch domes, described in hair-bearing skin in man and other mammals and must not be confused with focal hyperplastic or precancerous lesions.

Animals↗
PubMed1988

Ultrastructural identification of Merkel cells around the mouth of the newborn marsupial.

The ultrastructure of the epidermal cells surrounding the mouth of three newborn marsupial species, the Northern native cat Dasyurus hallucatus, the brush tail possum Trichosurus vulpecula and the Northern brown bandicoot Isoodon macrourus were examined. The presence of Merkel cells, highly sensitive touch receptors, would suggest that the sense of touch aids the relatively underdeveloped newborn marsupial to move from the urinogenital sinus to the pouch and to locate the teat.

Animals↗
PubMed1985

Merkel cell tumor with liver metastases: presentation as fulminant hepatic failure.

This report demonstrates that hepatic metastases can present with fulminant hepatic failure and that liver enzyme abnormalities may not become prominent until there has been massive replacement of the liver. The CT scan of liver may not demonstrate diffuse liver metastases as seen in this patient. Merkel cell tumor or trabecular neuroendocrine skin tumor is a previously unreported cause for the development of the syndrome of hepatic failure due to liver metastases.

Adenocarcinoma↗