Merkel cell carcinoma, also known as neuroendocrine carcinoma of skin is now well recognized entity of malignant skin tumor to clinicians and pathologists. A few cases have been reported up to now in the literature, but the information regarding the appropriate treatment modalities have not been obtained in detail. The clinical, histologic and ultrastructural features and the treatment of a case of primary Merkel cell carcinoma of eyelid in a 75 year-old male is presented.
Aged ; Carcinoma, Merkel Cell* ; Carcinoma, Neuroendocrine ; Eyelids* ; Humans ; Male ; Skin

Neuroendocrine neoplasms have been described in virtually every organ where neuroendocrine cells are distributed throughout the body. It commonly exhibits multiple lines of divergent differentiation. We report a case of neuroendocrine carcinoma occurring in a 52-year-old woman. She had multiple subcutaneous nodules on the trunk. The light microscopic appearance and immunohistochemical stains were consistent with a neuroendocrine carcinoma. But it showed some differences from Merkel cell carcinoma in clinical and immunohistochemical findings. It may be strongly suggested that it was probably metastatic neuroendocrine carcinoma.
Carcinoma, Merkel Cell ; Carcinoma, Neuroendocrine* ; Coloring Agents ; Female ; Humans ; Middle Aged ; Neuroendocrine Cells

Merkel cell carcinoma (MCC) is a rare, frequently lethal, primary neuroendocrine carcinoma of the skin. Histopathologically, it appears as a dermal nodule of small undifferentiated malignant cells. Historically, MCC was considered to be an eccrine carcinoma. Recognition of its neuroendocrine features later led to the hypothesis that it arose from Merkel cells in the skin, although recent evidences revisit the question of an epithelial origin. We recently experienced a Mercel cell carcinoma. So, we report a MCC case originated from skin in renal transplant patient who was administrated immunosuppressive agent.
Carcinoma, Merkel Cell* ; Carcinoma, Neuroendocrine ; Humans ; Kidney Transplantation ; Merkel Cells ; Skin ; Tacrolimus

Metastatic small cell neuroendocrine carcinomas(MSCNC) from distant sites, such as the lung, are high grade tumors with poor prognosis. Histopathologically, it is difficult to distinguish between MSCNC and Merkel cell carcinoma solely on the basis of histologic morphology, electron microscopy, and immunohistochemistry. In recent years, differential expression of cytokeratin(CK) 20 and thyroid transcription factor(TTF)-1 has been proposed as useful distinguishing features. It must be emphasized that clinical correlation(e.g. symptomatology, chest X-ray) and a combination of CK 20 and TTF-1 markers, are essential to differentiate these two disease entities. We herein present a case of MSCNC of the lung that might be misdiagnosed as Merkel cell carcinoma.
Carcinoma, Merkel Cell* ; Carcinoma, Neuroendocrine* ; Immunohistochemistry ; Lung* ; Microscopy, Electron ; Prognosis ; Thorax ; Thyroid Gland

Merkel cell carcinoma (MCC), a rare primary cutaneous small cell neuroendocrine carcinoma, is a tumor with distinct cytological features. In many cases, immunohistochemical staining (IHC) is required for the differentiation from other small round cell malignancies. Here we describe the cytological findings of Merkel cell carcinoma; these findings contributed to the diagnosis prior to performing IHC. A lower eyelid mass was excised and submitted for frozen section diagnosis. The frozen section diagnosis was consistent with a malignancy, but the more specific diagnosis was limited by the lack of specific histological features. Touch imprint cytology revealed a high cellularity with loosely cohesive small to large sized cells. The tumor cells showed hyperchromatic nuclei with fine chromatin and inconspicuous nucleoli, and thin-rimmed-cytoplasm including the characteristic eosinophilic button-like paranuclear inclusion, previously described as a pathognomonic cytological finding of MCC; this was not found in the H&E frozen section. In conclusion, we suggest that the touch imprint cytology may help in the differential diagnosis of small round cell neoplasms prior to performing IHC especially in frozen section diagnosis.
Carcinoma, Merkel Cell* ; Carcinoma, Neuroendocrine ; Chromatin ; Diagnosis* ; Diagnosis, Differential ; Eosinophils ; Eyelids ; Frozen Sections*

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine carcinoma of the skin that shows locoregional or distant metastasis. Metastasis of MCC to body cavity effusion is extremely rare; only three cases have been reported so far. Metastatic MCC in effusion cytology shows small blue round cells with fine stippled chromatin like other small blue round cell tumors such as small cell lung carcinoma or lymphoma. The diagnosis of metastatic MCC can grant patients good chances at recently advanced therapeutic options. Here, we present a case of metastatic MCC to pleural effusion with characteristic single file-like pattern.
Carcinoma, Merkel Cell ; Carcinoma, Neuroendocrine ; Chromatin ; Diagnosis ; Financing, Organized ; Humans ; Lymphoma ; Neoplasm Metastasis ; Pleural Effusion ; Skin ; Small Cell Lung Carcinoma

Merkel cell carcinoma is a neuroendocrine tumor of the skin and mucosa;it typically develops on sun-exposed areas in the head, neck, and upper extremities.It is difficult to distinguish Merkel cell carcinoma from any other lid carcinomas.Merkel cell carcinoma has a tendency to spread to the regional tissue, lymphatics, and systemic organs.Because of its poor prognosis, early diagnosis and appropriate treatment by wide surgical excision is necessary. We report two cases of Merkel cell carcinoma.One case is Merkel cell carcinoma involving right upper eyelid and parotid gland which was diagnosed clinically and histologically. The patients was managed by wide surgical resection and radiotherapy.The other case is Merkel cell carcinoma involv-ing the eyelid with extension to retrobulbar space and neck.
Carcinoma, Merkel Cell* ; Early Diagnosis ; Eyelids* ; Head ; Humans ; Neck* ; Neuroendocrine Tumors ; Parotid Gland ; Prognosis ; Skin

Merkel cell carcinoma is a rapidly growing malignant neuroendocrine tumor with a high rate of recurrence and metastasis for which wide excision is recommended. About 10 cases of spontaneous regression have been reported in the world. We report a case of Merkel cell carcinoma which showed spontaneous regression. The patient was a 68-year-old woman with a two-month history of a rapidly enlarging dusky red tumor on her right cheek. Microscopically, the tumor cells were uniform with round to oval shaped nucleus and scanty cytoplasm, and showed trabecular arrangement. Ultrastructually, dense core neurosecretory granules 100 to 200nm in diameter were found in the cytoplasm of tumor cells. As far as we know, this is the first case of the spontaneous regression of the tumor in the country.
Aged ; Carcinoma, Merkel Cell* ; Cheek ; Cytoplasm ; Female ; Humans ; Neoplasm Metastasis ; Neuroendocrine Tumors ; Recurrence

Merkel cell carcinoma is a malignant neuroendocrine tumor with a high rate of recurrence and metastasis. However, approximately 23 cases of spontaneous regression have been reported. We report a case of Merkel cell carcinoma which showed spontaneous regression. The patient was an 84-year-old male with a large red-colored, hemispheric tumor on the left inner thigh which had been presented for a year. We planned to perform surgery, but the tumor suddenly started to regress spontaneously. The size of the tumor decreased, the surface was flattened, and the color changed from red to brown. The lesion finally appeared as a brownish flat plaque. Excision of the regressed tumor was performed; immunohistopathological analysis showed CD3+ T cells infiltrating around the regressed merkel cell carcinoma.
Carcinoma, Merkel Cell ; Humans ; Male ; Neoplasm Metastasis ; Neuroendocrine Tumors ; Recurrence ; T-Lymphocytes ; Thigh

Merkel cell carcinoma (MCC) is a rare neuroendocrine tumor of the skin initially believed to arise from the Merkel cells. In the community setting a general radiation oncologist may only encounter this pathology in a handful of cases over the course of their career. Due to the low incidence of this malignancy, few prospective randomized controlled trials have ever been conducted and therefore guidelines are based on relatively lower levels of evidence upon which the clinical recommendations are made. We discuss the case of a female in her 90s presenting with a classic MCC primary lesion, as well as satellite lesions proximal to both the primary and the draining regional lymph nodes with no evidence of nodal involvement. Here we discuss the presentation, management, treatment planning, underlying pathology, results and sequelae of treatment. We also review new treatment modalities, and the most current staging systems and guidelines.
Carcinoma, Merkel Cell ; Female ; Hand ; Humans ; Incidence ; Lymph Nodes ; Merkel Cells ; Neuroendocrine Tumors ; Pathology ; Prospective Studies ; Skin