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Examination of barbels of the carp (Cyprinus carpio) revealed cells showing the characteristics of Merkel cells. Some ultrastructural features of these cells suggest a secretory function.
Examination of the labial epidermis of the lizard Lacerta sicula revealed cells displaying all features of Merkel cells. These cells are located in the stratum basale of epidermal pegs and are arranged in clusters.
An 89-year-old female with a two-year history of a growing tumor of the skin on her left thigh was subjected to fine needle aspiration. Cytologic examination of the aspirate revealed a small-cell carcinoma, and a Merkel-cell carcinoma was suggested. The diagnosis was confirmed by histopathologic and electron microscopic analysis of the removed tumor. The cytologic findings are presented and correlated with the light and electron microscopic pictures of the operative specimen.
Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine carcinoma. It has a propensity for both locoregional and distant recurrence despite treatment. We describe the case of a 51-year-old man diagnosed with MCC of the left forehead. At 14 months post surgery and adjuvant radiotherapy he developed an isolated deposit of metastatic MCC in the paraspinal soft tissues of his lower back. This atypical site of metastatic disease was treated with radiotherapy and combination chemotherapy. Atypical and isolated sites of metastatic MCC, although infrequently reported, highlight the often bizarre nature of this aggressive skin cancer. Treatment in such cases needs to be individualized.
Merkel cells carcinoma (MCC) is an uncommon skin lesion, considered a malignancy of the neuroendocrine system, which is found mainly in elderly people. Its incidence is highly correlated with sun exposure or immunodeficiency syndromes. MCC is often an aggressive tumour with high tendency for local recurrence, lymph node involvement and distant metastasis. To our best knowledge 20 cases originated from the auricle have been described, 2 of them arising from external ear canal. The authors report a case of the ear canal characterized by two others synchronous tumours and the occurrence of a malignant high grade lymphoma, in which contribute of the pathologist was essential for a critical review. MCC diagnosis is not always easy for its pathological and clinical features and it should always be considered in presence of lymphoma. A multidisciplinary approach is basic.
Merkel cell carcinoma is a highly malignant skin tumour that must be managed in a multidisciplinary forum. Excisional biopsy of the primary is recommended and this should be followed by postoperative radiotherapy to the primary site, in-transit areas and the draining lymph nodes. The tumour is quite radiosensitive and radiation doses of the order of 50 Gy offer high levels of local control. Resection margins of 3 cm are not required provided postoperative radiotherapy is used. In the event of inoperable disease, patient refusal of surgery or a frail patient, radiotherapy should be used as the sole treatment modality, with high likelihood of achieving local control. Patients with involved nodes have a higher risk of distant disease. Traditionally, involved nodes have been managed with resection but, currently, there are protocols exploring the use of synchronous chemoradiotherapy as definitive treatment. Although adjuvant chemotherapy has been used in this setting to reduce the risk of distant seeding, the benefits at this stage have not been confirmed conclusively. The presence of distant disease carries a grave outlook and responses to chemotherapy occur frequently, but are usually shortlived.
BACKGROUND: Although Merkel cell carcinoma (MCC) exhibits specific clinical and histologic features, differentiation from other cutaneous neoplasms, such as lymphoma, metastatic oat cell carcinoma and malignant melanoma (MM), may sometimes be difficult. OBJECTIVE: The aim of our study was to immunohistochemically differentiate MCC from MM. METHODS: Paraffin sections from 6 cases of primary MCC and 6 cases of primary MM were investigated. For immunostaining, the APAAP method was used. RESULTS: Neuron-specific enolase was positive in all cases of MCC, as well as in 2 cases of MM. Marked positivity for cytokeratins 18, 20 and chromogranin A was observed in the MCC group, whereas a complete absence of expression of these three markers was noted in the MM group. Immunostaining with HMB45 and NKI/C3 was positive in all cases of MM and negative in all cases of MCC. S-100 protein was positive in all but 1 case of MM. In contrast, only 1 case of MCC reacted with S-100 protein. CONCLUSION: Our results underline the role of immunohistochemistry in the diagnosis and differential diagnosis of MCC. In particular, the combination of neuron-specific enolase, cytokeratins 18, 20 and chromogranin A positivity for MCC and HMB45, NKI/C3 and S-100 protein positivity for MM is of great value in the distinction between these two cutaneous neoplasms.
BACKGROUND: Merkel cell (neuroendocrine) carcinoma (MCC) is a very aggressive primary cutaneous neoplasm occurring most often on the head and neck of the elderly. Complete spontaneous regression (CSR) of MCC was first described in 1986. Since then other cases have been reported bringing the total to 10. OBJECTIVE: To review these 10 cases and obtain long-term follow-up data, to compare them for similarities and differences. METHOD: Each original case report was extensively reviewed and authors contacted in most cases for confirmation and updated information. RESULTS: In no case did MCC recur after CSR was noted, although follow-up information in some cases was short. When CSR occurred, it was swift and dramatic with complete regression of skin and lymph node metastasis in 1-3 months. CONCLUSION: While only 10 cases of CSR is a small number, MCC is itself a rare malignancy with just over 600 reported cases. Today most cases of MCC receive aggressive combined therapy effectively precluding diagnosis of CSR. The nature of regression in these 10 cases may point toward future immunologic therapy just as similar cases of CRS in patients with melanoma have led to advances in the immunologic treatment for that malignancy.
Twenty-seven tumor specimens from patients with Merkel cell carcinoma (MCC) were tested for chemosensitivity against a battery of nine cytotoxic drugs in a short-term antimetabolic assay measuring inhibition of thymidine incorporation. Dose-response curves were constructed by plotting drug concentration in micrograms/ml versus % control [3H]thymidine incorporation. Specimens were considered 'sensitive' to a drug if, at the approximate peak plasma concentration (PPC), the inhibition of [3H]thymidine was greater than 50% when compared with untreated control primary cultures. The assay revealed a 'sensitive' tumor in 19 of 20 specimens and 16 of 17 patients had a tumor that was 'sensitive' to at least one drug tested in the assay system. The highest sensitivity in order of frequency was found with doxorubicin, epirubicin, cyclophosphamide, etoposide and cisplatin. At least 40% of the tumors were 'sensitive' to these five drugs. Cyclophosphamide was chosen as the most active drug (at PPC) in 10 of 19 assays (53%), etoposide in seven of 17 (41%), doxorubicin in four of 19 (21%), chlorambucil in one of 12 (8%) and cisplatin in one of 18 (5%) of assays. Though our results are preliminary, we have identified for the first time a range of cytotoxic drugs which appear effective against MCC in vitro. Our main task now is to determine whether our in vitro predictive assay will correlate with clinical benefit to the patient.
INTRODUCTION: Merkel cell carcinoma (MCC) is a rare skin tumor with a highly malignant nature whose appropriate treatment is still debated. Wide surgery is the treatment of choice, but the question concerning protocols for adjuvant radiotherapy or chemotherapy remains open. PATIENTS AND METHODS: A retrospective analysis of 24 cases of MCC collected over a period of 9 years was performed, focusing on clinical and histologic features, and response to treatment. RESULTS: There were 17 women and 7 men with a mean age of 74.3 years. The median follow up was 34 months. The annual incidence per 100,000 habitants was 0.378. The head and neck localization was predominant (54%). Fifteen (68%) of patients presented with local disease (stage I), and 32% of patients presented with regional node (stage II) or distant metastases (stage III). Patients with stage I had a 5-years overall survival rate of 73,85%. Among them, five patients (33%) developed a local or nodal recurrence, although two patients were initially treated with surgery and local post-operative radiotherapy. Patients with stage II and III demonstrated a 5-year overall survival rate of 51,43%. DISCUSSION: Our series illustrates the clinical characteristics of this tumor of the elderly, which is mainly located on head and neck and associated with a poor prognosis. Treatments are discussed.
A latticee or rodlet inclusion is occasionally observed in the nucleus of a Merkel cell. The lattice has the external form of a plaque or band and internally consists of alternating parallel wide and narrow layers. Filaments in wide layers run in at least two directions across the short dimension of the inclusion. In contrast, the rodlet is a bundle of parallel filaments running the long dimension of the inclusion. Filaments in lattices and rodlets possibly contract and agitate the highly folded nucleus of the Merkel cell.
The clinical, histopathologic, and ultrastructural features of a primary cutaneous vulvar neuroendocrine neoplasm (Merkel cell carcinoma) are presented. This recently described tumor arises in the dermis and is often aggressive with metastasis to regional lymph nodes. Ultrastructural study of this case reveals morphologic similarities to normal cutaneous Merkel cells, including peripherally located dense-core neurosecondary-like granules, and immunohistochemical studies revealed ACTH within neoplastic cells. By light microscopy this tumor is readily confused with other primary or metastatic cutaneous neoplasms; therefore, the importance of electron microscopic examination is emphasized for definitive diagnosis of this unusual tumor.
The existence of different neuroendocrine markers was investigated by immunocytochemistry in a case of Merkel cells tumor. Neuroplastic cells contain NSE,NF,CK and chromogranin A i.r. On the basis of the results the neuroendocrine nature of this uncommon neoplasm of the skin is confirmed and it is suggested that chromogranin A could represent an additional marker for Merkel cells tumors.
We report a case of neuroendocrine (Merkel cell) carcinoma (NC) of the skin, associated with a trichilemmal cyst, showing pagetoid spread into the trichilemmal epithelium. The association of the two lesions may strengthen the hypothesis that NC originates from pluripotent stem cells of adnexal epithelium.
The clinical courses of six patients treated with cytotoxic chemotherapy for recurrent Merkel cell tumor of the skin are reported. All patients experienced prompt clinical responses to chemotherapy (five complete response [CR], one partial response [PR]) and three patients (50%) have achieved long-term disease-free remission. The report highlights (1) the aggressive nature of Merkel cell skin cancer, (2) the highly chemosensitive nature of the disease, and (3) some practical problems in administering chemotherapy to elderly patients.
The identification of malignancies associated with transplantation has led to enhanced vigilance and care in these patients, as well as insight into the pathogenesis of select malignancies. We report a case of Merkel cell carcinoma, an uncommon cutaneous malignancy of neuroendocrine origin, diagnosed in a 65-year-old Caucasian man 6 years after renal transplantation. While it is well known that transplant patients are at increased risk for squamous cell carcinomas of the skin, other types may also have an increased frequency. We suggest that Merkel cell carcinoma could have an increased incidence in the transplant population.
Merkel's tumor cells represent a rare neuroendocrine neoplasia type which belong to an apudomi group but it's different due to the absence of the biogen amine and hormone polypeptide production. The authors report a rare case of Merkel's tumor cells clinically evident with a great neoformation under the left axilla but already represents at the moment of discovery a notable diffusion with repetition as in hepatic and suprarenal gland. Pointing out not only clinic case having arrived at their observance but also it's important to take note of this particular neoplasia and to suspect it in case of doubt interpretation of clinical tumor.
Fine needle aspiration (FNA) biopsy was performed on an intraparotid lymph node metastasis of a Merkel cell carcinoma of the eyelid in a 15-year-old girl with antecedent ectodermal dysplasia syndrome. The cytologic appearance of the aspirate and the results of immunocytochemical typing of intermediate filaments on the FNA smears provided a definitive diagnosis. The Romanowsky stain provided an excellent delineation of paranuclear intracytoplasmic "buttons," which appeared to contain both cytokeratin and neurofilaments by immunocytochemical studies. These findings confirm previous data emphasizing the role of light microscopic observations, supplemented by proper immunocytochemical investigations, in the differential diagnosis of metastatic Merkel cell carcinoma in fine needle aspirates.