Metastatic Merkel Cell Carcinoma After Simultaneous Pancreas-Kidney Transplantation: Fatal Outcomes.

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous malignancy. Immunosuppression increases the risk of MCC and is associated with poor prognosis. Organ transplant recipients (OTR) have worse overall survival (OS) than patients with immunosuppression due to other causes. Treating MCC after organ transplantation is challenging, as checkpoint inhibitor immunotherapy, the standard of care for treating MCC, increases the risk of transplant rejection. This paper reviews the cases of two simultaneous pancreas-kidney transplant (SPKT) recipients with MCC and explores the role of immunosuppression in the development of MCC. Immunosuppression was discontinued and checkpoint inhibitor therapy was initiated in the first patient and considered by the second patient. In both cases, treatment failed, and the patients died shortly after developing metastatic MCC. These cases illustrate the need for improved multidisciplinary treatment regimens for MCC in OTRs. J Drugs Dermatol. 2024;23(5):376-377.     doi:10.36849/JDD.8234  .

Unusual Metastasis to Eyelid from Extraocular Merkel Cell Carcinoma.

Merkel cell carcinoma (MCC) is an unusual skin tumor that has a significant rate of distant and local metastases. It is known that primary MCC of the eyelid usually occurs at the upper eyelid. Here we report an unusual case of MCC metastasis to the eyelid. A 63-year-old male was diagnosed with MCC three years earlier after initially presenting with a mass in his right thigh. After histopathological diagnosis, the patient received medical therapy. During treatment, he developed multiple distant metastases and a firm, purple, vascularized lesion on the upper eyelid. We confirmed the lesion was an eyelid metastasis of MCC by histopathological examination and imaging methods. This case shows that extraocular MCC can metastasize to the eyelids, particularly the upper eyelid, where primary periocular MCC usually appears.

Systematic evaluation of Merkel cell carcinoma clinical practice guidelines using the AGREE II instrument.

Merkel cell carcinoma (MCC) is a rare type of skin cancer that requires a multidisciplinary approach with a variety of specialists for management and treatment. Clinical practice guidelines (CPGs) have recently been established to standardize management algorithms. The objective of this study was to appraise such CPGs via the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument. Eight CPGs were identified via systematic literature search following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Four appraisers trained in AGREE II protocols evaluated each CPG and deemed two CPGs as high quality, five as moderate quality, and one as low quality. Intraclass correlation coefficients (ICCs) were calculated to verify reviewer consistency as excellent, good, and moderate across four, one, and one domain, respectively. The majority of MCC CPGs are lacking in specifying stakeholder involvement, applicability, and rigor of development. The two high quality CPGs are from the Alberta Health Services (AHS) and the collaboration between the European Dermatology Forum, the European Association of Dermato-Oncology, and the European Organization of Research and Treatment of Cancer (EDF/EADO/EORTC). The EDF/EADO/EORTC CPG had the highest overall score with no significant deficiencies across any domain. An important limitation is that the AGREE II instrument is not designed to evaluate the validity of each CPG's recommendations; conclusions therefore can only be drawn about each CPG's developmental quality. Future MCC CPGs may benefit from garnering public perspectives, inviting external expert review, and considering available resources and implementation barriers during their developmental stages.

Merkel cell carcinoma overlapping Bowen's disease: two cases report and literature review.

PURPOSE: Merkel cell carcinoma (MCC) is a rare neuroendocrine tumor of the skin, which mainly occurs in the sun exposed sites of white patients over 65 years, with a higher recurrence and metastasis rate. Clinically, MCC overlapping Bowen's disease (BD) is a very rare subtype of MCC. Few cases in the literature have been described and the management is not well defined. We summarize and update the epidemiology, clinical and histopathological features, metastasis characteristics, local recurrence rate and management of it by presenting two cases of MCC overlapping BD and reviewing the literature over the last 11 years. DESIGN: We consulted databases from PubMed, ResearchGate and Google Scholar by MeSh "Merkel cell carcinoma" and "Bowen's disease", "Bowen disease" or "squamous cell carcinoma in situ", from January 2013 to December 2023 and reviewed the literatures. We reported two additional cases. RESULTS: Total 13 cases of MCC overlapping BD were retrospectively analyzed, in whom mainly in elderly women over 70 years, the skin lesions were primarily located on the faces, followed by the extremities and trunk. Most of them were asymptomatic, firm, dark red nodules arising on rapidly growing red or dark brown patches, or presenting as isolated nodules. Dermoscopy evaluation was rarely performed in the pre-operative diagnostic setting. All cases were confirmed by histopathology and immunohistochemistry. The most definitive treatment was extended local excision, but local recurrences were common. Of the 13 cases, 4 cases experienced local or distant metastasis. One suffered from an in-transit recurrence of MCC on the ipsilateral leg after local excision and lymph node dissection, whose metastasis completely subsided after avelumab treatment and without recurrence or metastasis during 6 months of follow-up. CONCLUSIONS: MCC overlapping BD is a very rare skin tumor mainly predisposed on the faces, with high misdiagnosis rate and recurrence rate. Advanced disease at diagnosis is a poor prognostic factor, suggesting that earlier detection may improve outcome. The acronym, AEIOUN, has been proposed to aid in clinical identification. Our reports and the literature review can provide a better awareness and management of it.

The diagnostic utility of Merkel cell polyoma virus immunohistochemistry in cytology specimens.

OBJECTIVE: Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine neoplasm that predominantly affects elderly and immunocompromised patients. Merkel cell polyoma virus (MCPyV) is clonally integrated into the majority of MCCs and has been linked to patient outcomes, playing a central role in the pathogenesis of the disease. We aimed to assess the utility of MCPyV immunohistochemistry (IHC) in the diagnosis of MCC in cytology cell block specimens and correlating with clinicopathologic features. METHODS: Fifty-three cytology samples of MCC with sufficient cell block material were stained for MCPyV by IHC and scored semi-quantitatively in extent and intensity. Morphologic mimics of MCC including small cell lung carcinoma (n = 10), non-Hodgkin lymphoma (n = 10), basaloid squamous cell carcinoma (n = 6) and other neuroendocrine carcinomas (n = 8) were stained in parallel. Positive staining was defined as >1% of the tumour cells showing at least moderate staining intensity. RESULTS: The cytologic features of MCC were characterized by high nuclear-cytoplasmic ratios, hyperchromatic nuclei with 'salt and pepper' chromatin, and nuclear moulding. MCPyV was detected in 24 of 53 cases (45%). Staining was strong and diffuse in roughly half of the positive samples. Of the morphologic mimics, one follicular lymphoma showed strong and diffuse staining. In contrast to prior studies, we saw no association between MCPyV status and patient outcomes. CONCLUSION: Merkel cell polyoma virus IHC is highly specific (97%) for the diagnosis of MCC in our cohort, and can serve as a useful diagnostic tool for distinguishing MCC for morphologic mimics.

Neoadjuvant PD-1 Inhibitors: A Tale of Two Cases.

Treatment responses for locally advanced cutaneous squamous cell carcinoma (cSCC) and Merkel cell carcinoma (MCC) are often short lived and are marred with recurrences. The introduction of adjuvant PD-1 inhibitors has demonstrated significant improvement in both, response rates, and duration of response. For patients with high-risk resectable disease, adjuvant treatments have not demonstrated an ability to reduce recurrence risk. However, there is an opportunity in the neoadjuvant setting to alter recurrence risk. Here we dem-onstrate two cases of neoadjuvant treatment of cSCC and MCC with impressive results.  J Drugs Dermatol. 2024;23(2):     doi:10.36849/JDD.7043e.

NCCN Guidelines® Insights: Merkel Cell Carcinoma, Version 1.2024.

The NCCN Guidelines for Merkel Cell Carcinoma (MCC) provide recommendations for diagnostic workup, clinical stage, and treatment options for patients. The panel meets annually to discuss updates to the guidelines based on comments from expert review from panel members, institutional review, as well as submissions from within NCCN and external organizations. These NCCN Guidelines Insights focus on the introduction of a new page for locally advanced disease in the setting of clinical node negative status, entitled "Clinical N0 Disease, Locally Advanced MCC." This new algorithm page addresses locally advanced disease, and the panel clarifies the meaning behind the term "nonsurgical" by further defining locally advanced disease. In addition, the guideline includes the management of in-transit disease and updates to the systemic therapy options.

Merkel cell carcinoma recurrence risk estimation is improved by integrating factors beyond cancer stage: A multivariable model and web-based calculator.

BACKGROUND: Merkel cell carcinoma (MCC) recurs in 40% of patients. In addition to stage, factors known to affect recurrence risk include: sex, immunosuppression, unknown primary status, age, site of primary tumor, and time since diagnosis. PURPOSE: Create a multivariable model and web-based calculator to predict MCC recurrence risk more accurately than stage alone. METHODS: Data from 618 patients in a prospective cohort were used in a competing risk regression model to estimate recurrence risk using stage and other factors. RESULTS: In this multivariable model, the most impactful recurrence risk factors were: American Joint Committee on Cancer stage (P < .001), immunosuppression (hazard ratio 2.05; P < .001), male sex (1.59; P = .003) and unknown primary (0.65; P = .064). Compared to stage alone, the model improved prognostic accuracy (concordance index for 2-year risk, 0.66 vs 0.70; P < .001), and modified estimated recurrence risk by up to 4-fold (18% for low-risk stage IIIA vs 78% for high-risk IIIA over 5 years). LIMITATIONS: Lack of an external data set for model validation. CONCLUSION/RELEVANCE: As demonstrated by this multivariable model, accurate recurrence risk prediction requires integration of factors beyond stage. An online calculator based on this model (at merkelcell.org/recur) integrates time since diagnosis and provides new data for optimizing surveillance for MCC patients.

Exploring diagnosis and therapeutic complexities of an aggressive Merkel cell carcinoma: A case report and review of the literature.

Merkel cell carcinoma (MCC) is an aggressive and rare cutaneous neuroendocrine carcinoma that predominantly affects the sun-damaged skin of the head and neck region, extremities, and trunk of older white individuals. Microscopically, MCC is characterized by nests or sheets of uniform small round blue cells with scant cytoplasm, granular nuclei with a salt-and-pepper chromatin pattern, high proliferative activity, and occasional necrosis. They are usually positive for epithelial and neuroendocrine markers, particularly for cytokeratin 20 and AE1/AE3 in a paranuclear dot-like staining. We herein contribute by reporting a case of MCC affecting the auricular pavilion of a 66-year-old female patient from Campinas, Brazil. Additionally, a review of the current literature is also included to analyze all the cases that have been reported in the English-language literature, totalizing 27 cases of MCC on the external ear. The 5-year overall survival rate for individuals with localized MCC is 50% and the most common treatment choice is the combination of surgery with adjuvant radiotherapy and sentinel lymph node biopsy.

A review of Merkel cell carcinoma.

ABSTRACT: Merkel cell carcinoma (MCC) is a rare and aggressive type of metastatic, nonmelanoma skin cancer derived from Merkel cells in the epidermis. MCC can be induced by sun exposure or via Merkel cell polyomavirus (MCV) gene expression. MCV is found in most patients with MCC and is associated with a lower recurrence rate of MCC. MCC has a wide range of clinical presentations that make diagnosis challenging. Histologic examination is performed using unique markers to differentiate it from other diagnoses. This article reviews the pathogenesis, clinical presentation, histopathology, differential diagnosis, and treatment of MCC.

Risk of Multiple Primary Cancers in Patients With Merkel Cell Carcinoma: A SEER-Based Analysis.

Importance: The risk of subsequent primary cancers after a diagnosis of cutaneous Merkel cell carcinoma (MCC) is not well established. Objective: To evaluate the risk of subsequent primary cancers after the diagnosis of a first primary cutaneous MCC. Design, Setting, and Participants: This cohort study analyzed data from 17 registries of the Surveillance, Epidemiology, and End Results (SEER) Program from January 1, 2000, to December 31, 2019. In all, 6146 patients diagnosed with a first primary cutaneous MCC were identified. Main Outcomes and Measures: The primary outcome was the relative and absolute risks of subsequent primary cancers after the diagnosis of a first primary MCC, which were calculated using the standardized incidence ratio (SIR; ratio of observed to expected cases of subsequent cancer) and the excess risk (difference between observed and expected cases of subsequent cancer divided by the person-years at risk), respectively. Data were analyzed between January 1, 2000, and December 31, 2019. Results: Of 6146 patients with a first primary MCC diagnosed at a median (IQR) age of 76 (66-83) years, 3713 (60.4%) were men, and the predominant race and ethnicity was non-Hispanic White (5491 individuals [89.3%]). Of these patients, 725 (11.8%) developed subsequent primary cancers, with an SIR of 1.28 (95% CI, 1.19-1.38) and excess risk of 57.25 per 10 000 person-years. For solid tumors after MCC, risk was elevated for cutaneous melanoma (SIR, 2.36 [95% CI, 1.85-2.97]; excess risk, 15.27 per 10 000 person-years) and papillary thyroid carcinoma (SIR, 5.26 [95% CI, 3.25-8.04]; excess risk, 6.16 per 10 000 person-years). For hematologic cancers after MCC, risk was increased for non-Hodgkin lymphoma (SIR, 2.62 [95% CI, 2.04-3.32]; excess risk, 15.48 per 10 000 person-years). Conclusions and Relevance: This cohort study found that patients with MCC had an increased risk of subsequently developing solid and hematologic cancers. This increased risk may be associated with increased surveillance, treatment-related factors, or shared etiologies of the other cancers with MCC. Further studies exploring possible common etiological factors shared between MCC and other primary cancers are warranted.

Cytokeratin-20 negative nodal Merkel cell carcinoma with regressed primary: a potential pitfall in interpretation of nodal metastasis.

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous neuroendocrine carcinoma that affects sun-damaged skin. Histologically, the tumor consists of round cells with fine chromatin positive for cytokeratin 20 in ~90% of cases. Rare cases of MCC can regress spontaneously and present as nodal metastasis. Nodal MCC of unknown primary can cause a potential pitfall as they can be misinterpreted as other neuroendocrine carcinomas such as small cell carcinoma. We report a case of nodal MCC with an atypical immunohistochemistry pattern presented as bilateral axillary lymphadenopathy in a 90-year-old man with a remote history of a skin lesion that healed spontaneously leaving a scar.