An Unusual Presentation of Merkel Cell Carcinoma in a HIV Patient: A Case Report and Literature Review

The Evaluation and Treatment of Merkel Cell Carcinoma and Brain Metastasis: A Case Report and Review of the Literature

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor associated with high mortality if metastases are identified. Currently, there is no standardized nor curative treatment for neurometastatic MCC. In this study, we have reviewed the more recent cases and the use of immunotherapy in a population. In this case report and review, we present a case of MCC with brain metastasis currently undergoing treatment with immunotherapy (pembrolizumab) resulting in an initial complete response with a progression-free survival time of five months. We also review the past reported literature and the 11 newly presented cases on their clinical presentation of neurometastatic MCC, immunohistochemical markers, and treatment outcomes. In summary, immunotherapy initially showed a promising response with the complete elimination of MCC brain metastasis. The early aggressive treatment of pembrolizumab with stereotactic radiosurgery should be considered as this treatment plan has shown improved therapeutic effects compared to the standard chemoradiation therapy. Further investigations are needed to determine the efficacy and response of immunotherapy use for neurometastatic MCC.

Merkel cell carcinoma brain metastasis with radiological findings mimicking primary CNS lymphoma: illustrative case

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor with a high likelihood of distant metastasis. Approximately 30 cases of MCC brain metastasis have been reported. The authors report a case of MCC brain metastasis with imaging findings mimicking primary central nervous system lymphoma.

OBSERVATIONS

A 69-year-old asymptomatic White female with a past medical history of rheumatoid arthritis and MCC of the right cheek with no known regional or distant spread presented with a right frontal lobe lesion discovered incidentally on a surveillance scan. Brain magnetic resonance imaging revealed a vividly enhancing homogeneous lesion with restricted diffusion on diffusion-weighted imaging and corresponding apparent diffusion coefficient maps. Imaging characteristics suggested a highly cellular mass consistent with primary central nervous system lymphoma; however, given the likelihood of metastasis, resection was recommended. An intraoperative frozen section suggested lymphoma. However, further examination revealed positive cytokeratin 20 staining for a tumor, and a final diagnosis of MCC brain metastasis was made.

LESSONS

Imaging characteristics of MCC brain metastasis can vary widely. A high level of suspicion should be maintained in a patient with a known history of MCC. Aggressive resection is recommended, regardless of appearance on scans or pathology of frozen sections, because MCC can mimic other intracranial pathologies.

Long-term response to avelumab and management of oligoprogression in Merkel cell carcinoma: A case report

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine neoplasia, with high risk of recurrence and metastasis and poor survival. Immune checkpoint inhibitors, like the anti-programmed death-ligand 1 agent avelumab, were recently approved for the treatment of advanced MCC. We, herein, report the first case of advanced MCC with oligoprogression managed with avelumab and local radical treatment.

CASE SUMMARY

A 61-year-old man was presented to the hospital with sporadic fever and an exudative malodorous mass (10 cm of diameter), located on the right gluteal region. The final diagnosis was MCC, cT4N3M1c (AJCC, TNM staging 8^th edition, 2017), with invasion of adjacent muscle, in-transit metastasis, and bone lesions. Patient started chemotherapy (cisplatin and etoposide), and after six cycles, the main tumor increased, evidencing disease progression. Two months later, the patient started second line treatment with avelumab (under an early access program). After two cycles of treatment, the lesion started to decrease, achieving a major response. Local progression was documented after 16 cycles. However, as the tumor became resectable, salvage surgery was performed, while keeping the systemic treatment with avelumab. Since the patient developed bilateral pneumonia, immunotherapy was suspended. More than 2.5 years after surgery (last 19 mo without systemic therapy), the patient maintains complete local response and stable bone lesions.

CONCLUSION

This report highlights the efficacy and long-term response of avelumab on the management of a chemotherapy resistant advanced MCC, with evidence of oligoprogression, in combination with local radical treatment.

Primary ectopic Merkel cell carcinoma without skin involvement-report of a case with prolonged survival

Merkel cell carcinoma is a rare neuroendocrine malignancy that arises from the dermis, in cases of immunocompromised, middle-aged patients or on skin exposed to sunlight. It only rarely presents in extra-cutaneous locations. We present the case of a 63-year-old female with a mass in the adipose tissue of the upper arm, without skin involvement and concurrent axillary lymph node enlargement. She was treated with wide excision and lymph node dissection; pathology led to the diagnosis of Merkel cell carcinoma, and she was subsequently submitted to adjuvant radiotherapy. No signs of recurrence are present 8 years postoperatively. Primary Merkel cell carcinoma can rarely be located in the adipose tissue without skin involvement. In cases of high suspicion, preoperative MRI scan can show the extent of the lesion, as well as lymph metastases.

Clinical Features and Prognosis of Merkel Cell Carcinoma in Elderly Patients

BACKGROUND Merkel cell carcinoma (MCC) occurs primarily among elderly patients over 70 years old, but the ability to predict the prognosis of these elderly patients is poor. This population-based study aimed to identify prognostic risk factors for elderly patients with MCC. MATERIAL AND METHODS The survival and disease information of MCC patients age 65 years or older was downloaded from the SEER database, and all data were split into 2 groups based on age 80 years, with overall survival and MCC-specific survival as the main outcome indicators. RESULTS Application of the inclusion criteria yielded 1973 patients with MCC, of whom 55.6% were age 65-80 years. Among them, 1258 were males, accounting for 63.8%. In survival analysis, factors that were significantly correlated with overall survival and MCC-specific survival were N stage, M stage, liver metastasis, and lymph node surgery. CONCLUSIONS We provide epidemiological insights into Merkel cell carcinoma in elderly patients and confirmed that patients receiving lymph node surgery have better outcomes. To the best of our knowledge, this is the first study to show that the occurrence of liver metastasis is associated with poor prognosis. Our results will help strengthen monitoring of the liver condition of elderly patients and to perform necessary lymph node surgery within the patient's tolerance.