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

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

Merkel cell carcinoma (MCC) is a relatively rare and aggressive cutaneous neuroendocrine malignancy. It is characterized by high rates of recurrence and metastasis, both to regional lymph nodes and to distant locations. Its characteristic clinical manifestation is a single, painless, hard, erythematous nodule on a sun-exposed area, particularly in older men. Surgical management of both the primary site and the sentinel lymph node is the standard of care. In this article, we describe the diagnosis and treatment of a case of MCC in the left cheek.
Carcinoma, Merkel Cell ; Cheek ; Diagnosis ; Head ; Humans ; Lymph Nodes ; Male ; Merkel Cells ; Neck ; Neoplasm Metastasis ; Recurrence ; Skin Neoplasms ; Standard of Care

BACKGROUND: Protooncogene, bcl-2 is known to inhibit, apoptosis induced by various stimuli. Its expression has been reported in various fetal and adult tissues, and also in tumors of neural origin. OBJECTIVE: The purpose of this study was to evaluate the expression of bcl-2 in a skin tumor of neuroectodermal origin and to estimate whether this expression was useful in the different,ial diagnosis of tumors of neural origin or not. METHOD: Immunohistochemical stains by the LSAB(labelled streptavidin biotin) method for bcl-2 protein were performed in normal special nerve end-organs and a skin tumor of neural origin. RESULTS: The immunohistochemical findings revealed strong positive results in Meissners corpuscles, but weak week positive results in Vater-Pacini corpuscles. There were also strong positive results in neurilernmomas which were mostly composed of Schwann cells, but results were mostly negative in neurofibromas and neurofibrosarcomas which were composed primarily of endoneurial fibroblasts of mesodermal origin except a few cells of Schwann cell origin. Benign granular cell tumors arising from Schwann cells, and Merkel cell carcinoma known to arise from the Merkel cells of neural crest origin showed strong positive reactions. CONCLUSION: The strong expression of bcl-2 protein exclusively in the tumor of neuroectodermal origin suggests a useful indicator for the differential diagnosis of skin tumors of neural origin.
Adult ; Apoptosis ; Carcinoma, Merkel Cell ; Coloring Agents ; Diagnosis ; Diagnosis, Differential ; Fibroblasts ; Granular Cell Tumor ; Humans ; Merkel Cells ; Mesoderm ; Neural Crest ; Neural Plate* ; Neurofibroma ; Neurofibrosarcoma ; Schwann Cells ; Skin* ; Streptavidin

PURPOSE: Merkel cell carcinoma, also called neuroendocrine carcinoma, is a very rare type of skin cancer that develops as Merkel cells grow out of control. Merkel cell carcinoma is reported below 1% of whole skin neoplasms in the United States and is known that the 2-year survival rate is about 50~70%. The principles of treatment are wide excision of primary lesion with radiotherapy and/or chemotherapy that decrease the local recurrent rate. There has been no report of reconstruction with free flap after resection of Merkel cell carcinoma in Korea. METHODS: We reconstructed the skin and soft tissue defect after wide excision of Merkel cell carcinoma with anterolateral thigh perforator free flap in two cases. No distant metastasis was found at the preoperative imaging work-up. In one case, preoperative chemotherapy was performed and the size of lesion was decreased. RESULTS: There were no recurrence and significant complications. Functionally and aesthetically satisfactory results were obtained with reconstruction. CONCLUSION: Wide excision and reconstruction with anterolateral thigh perforator free flap for Merkel cell carcinoma patient is the first report in Korea. We regard this method as the treatment of choice in Merkel cell carcinoma.
Carcinoma, Merkel Cell ; Carcinoma, Neuroendocrine ; Free Tissue Flaps ; Humans ; Korea ; Merkel Cells ; Neoplasm Metastasis ; Recurrence ; Skin ; Skin Neoplasms ; Survival Rate ; Thigh ; United States

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroectodermal carcinoma arising from mechanoreceptor Merkel cells. Multiple MCCs are even rarer. We report a case of two independent MCCs simultaneously present in the cheek of a patient, which were effectively and esthetically treated using a cheek flap. Punch biopsy performed in a 60-year-old woman admitted with a chief complaint of two skin-colored hard nodules in her left cheek, accompanied by an itching sensation, was suggestive of MCC. Accordingly, we performed sentinel lymph node biopsy through the modified Blair incision under general anesthesia, in cooperation with the head and neck surgery department. The defect was covered with a cheek flap by slightly extending the existing incision following wide excision with a safety margin of 1 cm. This paper is significant in that it introduces an effective reconstruction technique that maintains function using a cheek flap for the management of this rare case. In addition, this paper is the first to classify multiple MCCs according to the time of onset. We believe that this paper presents an effective alternative reconstruction technique with sentinel node biopsy through the modified Blair incision.
Anesthesia, General ; Biopsy ; Carcinoma, Merkel Cell ; Cheek ; Female ; Head ; Humans ; Mechanoreceptors ; Merkel Cells ; Middle Aged ; Neck ; Neural Plate ; Pruritus ; Sensation ; Sentinel Lymph Node Biopsy ; Surgical Flaps

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

BACKGROUND: In the course of the study of keratin expression in the epidermis of nevus sebaceus, several cells in the epidermis of nevus sebaceus were positively stained with CAM 5.2 antibody, which is known to be specific for the lower molecular weight cytokeratin and used as a marker of Merkel cell. OBJECTIVE: This study was intended to verify that CAM 5.2 positive cells found in the epidermis of nevus sebaceus are Merkel cells and to understand the meaning of CAM 5.2 positive j cells in the epidermis of nevus sebaceus. METHODS: The immunohistochemical stainings with CAM 5.2 and antibody to epithelial membrane antigen (EMA) performed on specimens of normal skin, epidermal nevus, nevus sebaceus and some appendage tumors. In order to confirm the nature of CAM 5.2 positive cells, the distribution of those were compared to that of Merkel cells and double labeling with CAM 5.2 and neurofilament was performed. RESULTS: CAM 5.2 positive cells were also found in trichilemmoma developed associated with nevus sebaceus and the epidermis of normal paimoplantar skin. CAM 5.2 positive cells were also stained with antibody to EMA on serial sections cut from the same tissue blocks. The association of CAM 5.2 positive cell and nerve fiber was also demonstrated. CONCLUSION: CAM 5.2 positive cells are seemed to be Merkel cells and their presence in the covering epidermis of nevus sebaceus suggests to the epidermis of nevus sebaceus may not be nevoid proliferation of epidermal keratinocytes.
Epidermis* ; Intermediate Filaments ; Keratinocytes ; Keratins ; Merkel Cells ; Molecular Weight ; Mucin-1 ; Nerve Fibers ; Nevus* ; Skin

BACKGROUND: In the course of the study of keratin expression in the epidermis of nevus sebaceus, several cells in the epidermis of nevus sebaceus were positively stained with CAM 5.2 antibody, which is known to be specific for the lower molecular weight cytokeratin and used as a marker of Merkel cell. OBJECTIVE: This study was intended to verify that CAM 5.2 positive cells found in the epidermis of nevus sebaceus are Merkel cells and to understand the meaning of CAM 5.2 positive j cells in the epidermis of nevus sebaceus. METHODS: The immunohistochemical stainings with CAM 5.2 and antibody to epithelial membrane antigen (EMA) performed on specimens of normal skin, epidermal nevus, nevus sebaceus and some appendage tumors. In order to confirm the nature of CAM 5.2 positive cells, the distribution of those were compared to that of Merkel cells and double labeling with CAM 5.2 and neurofilament was performed. RESULTS: CAM 5.2 positive cells were also found in trichilemmoma developed associated with nevus sebaceus and the epidermis of normal paimoplantar skin. CAM 5.2 positive cells were also stained with antibody to EMA on serial sections cut from the same tissue blocks. The association of CAM 5.2 positive cell and nerve fiber was also demonstrated. CONCLUSION: CAM 5.2 positive cells are seemed to be Merkel cells and their presence in the covering epidermis of nevus sebaceus suggests to the epidermis of nevus sebaceus may not be nevoid proliferation of epidermal keratinocytes.
Epidermis* ; Intermediate Filaments ; Keratinocytes ; Keratins ; Merkel Cells ; Molecular Weight ; Mucin-1 ; Nerve Fibers ; Nevus* ; Skin

The reconstruction of tactile function during the repair of skin damage caused by factors including burns is inseparable from the functional regeneration of tactile receptor Merkel cells. Merkel cells mainly exist in the basal layer of the epidermis and are closely connected with nerves to form Merkel cell-nerve complexes, which play an important role in biological organisms. A large number of studies have shown that Merkel cells conduct precise transmission of mechanical force stimuli through the mechanically gated ion channels PIEZO2, and perform the function of tactile receptors. In this paper, we discussed the characteristics of Merkel cells and analyzed the different subgroups that may possibly exist in this type of cells and their functions, at the same time, we investigated the animal model research of touch-related diseases and the clinical diseases related to touch, revealing the importance of Merkel cell function research.
Animals ; Ion Channels/metabolism* ; Mechanotransduction, Cellular/physiology* ; Merkel Cells/physiology* ; Skin/metabolism* ; Touch/physiology*