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*

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

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

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

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

BACKGROUND: The epidermis and adnexal epithelium might express different types of keratin (K) during fetal development. OBJECTIVE: The objective is to observe the distribution of K8/18 in the skin of fetuses and to find out the distinction of expressions of K8/18 during fetal development. METHODS: Immunohistochemical analysis was applied to the skin of the scalp and sole of 42 fetuses ranging from 10 to 39 weeks of gestation. Immunohistochemical staining with monoclonal antibodies with CAM5.2 using LSAB kit against K8/18 was conducted. RESULTS: In the skin of the scalp, K8/18 was expressed in the periderm and basal layer of epidermis from the 10th week to the 31st week of fetal gestation. K8/18 was expressed in the hair germ, bulge and basal cells of fetal the infundibulum and sebaceous glands. Root sheath cells were weakly positive but matrix cells were negative. The expression of K8/18 was negative in the basal layer of the sole. Merkel cells, which are located in the basal layer and upper dermis, were positive from the 12th week of gestation. Terminal eccrine ducts and acinar cells were positive after the 20th week of gestation. CONCLUSION: K8/18 in the skin of the scalp and sole of fetuses were expressed in different ways. The expression of K8/18 in the basal cells of the sole were negative while basal cells of the epidermis of the scalp were positive transiently from the 12th to the 31st week of gestation. Early hair germ cells and bulge cells were expressed strongly in hair follicles. Terminal eccrine ducts and acini were expressed strongly in the eccrine gland. Merkel cells located in the basal layer and papillary dermis also express K8/18.
Acinar Cells ; Antibodies, Monoclonal ; Dermis ; Eccrine Glands ; Epidermis ; Epithelium ; Fetal Development ; Fetus ; Germ Cells ; Hair ; Hair Follicle ; Merkel Cells ; Molecular Weight* ; Pregnancy ; Scalp ; Sebaceous Glands ; Skin*

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 cells are thought to function as slowly adapting mechanoreceptors and are known as targets for sensory nerves. However, the nerve-dependency of Merkel cells remains controversial. In this respect, some investigators have found interregional differences between hairy and glabrous skin and others have shown intraregional differences within denervated rat touch domes. Differences between species have also been reported. This study was performed to determine whether Merkel cells proliferate in vitro in the absence of the systemic factors, blood vessels and the intact nerves in human skin. Suspension organ culture was performed using fetal digits to investigate their in vitro proliferation. Merkel cells and cutaneous nerves were identified using antibodies to cytokeratin 20 and protein gene product 9.5 (PGP 9.5), respectively. Fetal digits of 56-82 day gestational age were cultured in serum free medium in a high O2 (45%) environment. Tissues were harvested before starting culture (D0) and 1,4,7,14, 28d after culture. Merkel cells were observed in the volar pads and dorsal nail matrices at D0. After 28d of suspension organ culture, digits looked healthy structurally and the number of Merkel cells had increased. However, PGP 9.5-immunoreactive nerves were markedly diminished after 1 day of culture and almost disappeared after 4 days. Merkel cell proliferation in vitro suggested that Merkel cell development is probably nerve-independent in human fetal glabrous skin.
Cell Division ; Female ; Human ; Intermediate Filament Proteins/analysis ; Merkel Cells/*physiology ; Organ Culture ; Pregnancy ; Skin/cytology/*embryology/*innervation ; Thiolester Hydrolases/analysis

Merkel cell carcinoma is an uncommon malignancy originally called "trabecular carcinoma" by Toker in 1972. Although the exact origin of the Merkel cell is unknown, it probably arises from neuroendocrine cell of the basal epidermis. It then grows vertically into the dermis and subcutaneous tissue. The tumor usually affects older persons, with a median age at presentation of 66 years. Although its cause is unknown, its propensity to occur on the head, neck, or extremities suggests that sun exposure may play a role. We report a case of a 58-year-old woman who showed a solitary dusky red-colored tumor on the right upper arm. The tumor had rapidly grown since 2 months ago but there was no evidence of regional lymph node and distant metastases. Microscopically, the tumor cells were uniform with round to oval shaped nucleus and scanty cytoplasm, and showed trabecular, anastomosing cord-like arrangement mainly in the dermis and subcutaneous tissue. Ultrastructually, membrane-bound neurosecretory granules were found in the cytoplasm and characteristic perinuclear filaments were retained in each tumor cell. We performed wide local excision with 3cm margin and prophylactic radiation therapy.
Arm ; Carcinoma, Merkel Cell* ; Cytoplasm ; Dermis ; Epidermis ; Extremities ; Female ; Head ; Humans ; Lymph Nodes ; Middle Aged ; Neck ; Neoplasm Metastasis ; Neuroendocrine Cells ; Solar System ; Subcutaneous Tissue

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