Merkel cell carcinoma in situ: A systematic review of prognosis and management

Abstract

Background: Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine tumour. While dermally invasive MCC is known to have a five-year survival of only 30-40%, the prognosis and management of MCC in situ (MCCis) is not widely reported.Objective: We present a systematic review to elucidate the prognosis and management of MCCis. Methods:We performed a systematic review, searching three databases to 01 June 2021. Case reports, cohort studies, clinical trials and literature reviews were considered for inclusion. Results:We identified 26 cases of MCCis published in the literature with a median age of 74 years and involving 19 males and 7 females. Most cases were on the face and neck (n = 17), followed by upper limb (n = 8) and lower limb (n = 1). Sentinel lymph node biopsy was performed in three patients, and all were negative. One subject underwent adjuvant radiotherapy. No MCCis-associated deaths were reported. Conclusion:This review suggests that MCCis has an excellent prognosis with minimal, if any, risk of mortality and a very low risk of dermal invasion and recurrence when treated with wide local excision alone. Sentinel lymph node biopsy is unlikely to be useful for MCCis.

Merkel Cell Carcinoma In Situ Arising in Association With an Infundibular Cyst With Unusual Reticulated Infundibulocystic Proliferation

“…Sentinel lymph node biopsy is unlikely to be useful in MCCIS. 12 Our case was treated with wide local excision and is free of disease 1 year postexcision, supporting these findings .…”

“…Prognosis of MCC is poor with an overall 5-year survival rate for invasive MCC being 30%-40%. 12 MCPyVnegative MCCs have a worse prognosis and seem to be clinically more aggressive and present with more advanced disease than MCPyV positive MCCs. 13 With regard to MCCIS, the number of reported cases is small; however, in a systemic review of prognosis and management of MCCIS, 26 cases were identified.…”

Clinical-Pathological Evaluation and Prognostic Analysis of 228 Merkel Cell Carcinomas Focusing on Tumor-Infiltrating Lymphocytes, MCPYV Infection and ALK Expression

“…Only two cases displayed focal squamous differentiation, and further two were characterized by prominent glomeruloid vascular proliferations. Epidermotropism and/or MCC in situ [31] were not observed. Tumor cells displayed conventional neuroendocrine-like features in 59% of cases; the remaining cases were further described as large (25%), spindled (14%), and pleomorphic (2%).…”

MCPyV-Negative Merkel Cell Carcinoma In Situ Associated With Immunosuppression

“…5 Previously reported cases of MCCis suggest that it has an excellent prognosis and is associated with less risk of local recurrence or distant metastasis compared with MCC. 4 Of the 29 reported cases, there has been only 1 reported case of MCCis with local recurrence, whereas about one-third of patients with invasive MCC develop local or distant recurrence. Due to the small number of MCCis cases reported in the literature with long-term follow-up, MCCis should be managed similarly to MCC with surgical excision and sentinel lymph node biopsy.…”

“…1,2 Strictly intraepidermal MCC is extremely rare with only 29 reported cases in the literature thus far. 1,3,4 Most MCCis cases are associated with other cutaneous lesions, such as squamous cell carcinoma, trichilemmal cyst, seborrheic keratosis, and actinic keratosis. 2 Our case adds to 9 reported cases of MCCis without coexisting cutaneous neoplasm (Table 1).…”