Intracranial spread of Merkel cell carcinoma through intact skull

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.

Lack of association between anatomical sites of scalp melanomas and brain metastases does not support direct vascular spread

Primary scalp melanomas are associated with a higher rate of brain metastasis than primary cutaneous melanomas occurring at other head and neck and body sites, but the reason is unclear. Spread to brain parenchyma via emissary veins draining from the scalp to dural sinuses has been suggested. We sought to examine the locations of metastases from primary scalp and nonscalp head and neck melanomas to determine whether there was anatomical evidence supporting direct venous spread to the brain. Data from patients who developed distant metastases from cutaneous head and neck melanomas (CHNMs) between 2000 and 2018 were analyzed. Anatomical sites of primary scalp melanomas and their respective intracranial metastases were compared. Times to first brain and nonbrain metastases were investigated for scalp and nonscalp primary CHNMs. Of 693 patients with CHNMs, 244 developed brain metastases: 109 (44.7%) had scalp primaries and 135 (55.3%) had nonscalp primaries. There was no significant association between anatomical sites of scalp primary melanomas and brain metastases (Cramer's V = 0.21; Chi-square P = 0.63). Compared with nonscalp CHNMs, scalp melanomas had no greater propensity for the brain as the first distant metastatic site ( P = 0.52) but had a shorter time to both brain metastasis (76.3 vs. 168.5 months; P < 0.001) and nonbrain metastasis (22.6 vs. 35.8 months; P < 0.001). No evidence was found to support a direct vascular pathway for metastatic spread of scalp melanomas to the brain. The increased incidence of brain metastases from scalp melanomas is probably driven by aggressive biological mechanisms.

Imaging of Merkel Cell Carcinoma: What Imaging Experts Should Know

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine tumor with a higher mortality rate than melanoma. Approximately 40% of MCC patients have nodal or distant metastasis at initial presentation, and one-third of patients will develop distant metastatic disease over their clinical course. Although MCC is rare, its incidence has been steadily increasing. Furthermore, the immunogenicity of MCC and its diagnostic and therapeutic application have made MCC one of the most rapidly developing topics in dermatology and oncology. Owing to the aggressive and complex nature of MCC, a multidisciplinary approach is necessary for management of this tumor, including dermatologists, surgeons, radiation oncologists, medical oncologists, pathologists, radiologists, and nuclear medicine physicians. Imaging plays a crucial role in diagnosis, planning for surgery or radiation therapy, and assessment of treatment response and surveillance. However, MCC is still not well recognized among radiologists and nuclear medicine physicians, likely owing to its rarity. The purpose of this review is to raise awareness of MCC among imaging experts by describing the epidemiology, pathophysiology, and clinical features of MCC and current clinical management with a focus on the role of imaging. The authors highlight imaging findings characteristic of MCC, as well as the clinical significance of CT, MRI, sentinel lymph node mapping, fluorine 18 fluorodeoxyglucose PET/CT, and other nuclear medicine studies such as bone scintigraphy and somatostatin receptor scintigraphy. ^©RSNA, 2019.

Predictors of survival in neurometastatic Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy of neuroendocrine origin, with about 30 cases of brain metastasis (BM) reported in the literature. Historically, the treatment of neurometastatic MCC has largely included chemotherapy and radiotherapy. The aim was to investigate predictors of overall survival (OS) in neurometastatic MCC.

METHODS

In this retrospective study, we surveyed institutional databases and conducted a systematic review of the literature to identify cases reporting on management of distant MCC BM. A pooled survival analysis was performed on the institutional and literature cases to assess predictors of OS.

RESULTS

Forty cases were included for analysis, describing operative [14] and non-operative [26] management. Median time to central nervous system involvement was 17.0-mos (interquartile range 10.5-26.5), and most patients had a single BM (62.5%). Management of intracranial disease included radiotherapy (82.5%), systemic therapy (59.5%) and surgical resection (35%). Operative management was associated with a lower intracranial burden of disease (BoD), but similar systemic BoD. Both neurosurgery (hazard ratio [HR] 0.18, 95% confidence interval [CI]: 0.06-0.54, p = 0.002), having RT (HR 0.37, 95% CI: 0.14:0.93, p = 0.04) and having a single BM (extensive intracranial BoD: HR 2.51, 95% CI: 1.12-5.6, p = 0.03) conferred an OS benefit on risk-unadjusted analysis. Only, neurosurgical resection was an independent predictor of OS (HR 0.12, 95% CI: 0.03-0.49, p = 0.003), controlling for age, BoD and radiotherapy.

CONCLUSIONS

Resection of MCC BM may confer a survival benefit given appropriate patient selection. Prospective investigation of multimodal management of neurometastatic MCC is warranted, especially given the promise of new immunotherapy agents in treating MCC.

Merkel Cell Carcinoma with Distant Metastasis to the Clivus Causing Symptoms Mimicking Tolosa-Hunt Syndrome: A Case Report and Literature Review

Merkel cell carcinoma (MCC) is an uncommon but highly malignant neuroendocrine tumor of the skin. MCC can metastasize, but involvement of the central nervous system is rare. Here, we report a case of rapidly progressing metastatic MCC to the clivus and bilateral cavernous sinus in an immunocompromised patient. This case is unique in that it is the first case report showing MCC metastasis to the clivus from a distant site. It also demonstrates that a MCC metastasis can masquerade with symptoms of Tolosa–Hunt syndrome. A literature review on MCC with CNS metastasis is presented.

Systematic literature review of efficacy, safety and tolerability outcomes of chemotherapy regimens in patients with metastatic Merkel cell carcinoma

AIM

Merkel cell carcinoma (MCC) is a rare neuroendocrine, cutaneous malignancy with poor prognosis once metastasized. The aim of this study was to conduct a systematic literature review to assess clinical outcomes associated with chemotherapy regimens in metastatic MCC.

MATERIALS & METHODS

Embase^®, MEDLINE^®, MEDLINE^®-In-Process and CENTRAL were searched for studies published in January 2016.

RESULTS & CONCLUSION

Overall, the literature on chemotherapy in patients with metastatic MCC is sparse, with most studies being case series/reports. Across all studies, response rates ranged from 20 to 61%, with higher response rates in first-line setting (53-61%) versus second-line setting (23-45%). Among responders, duration of response was short (≤8 months) in both first- and second-line settings. There is a need for novel agents that can induce durable responses in metastatic MCC.

Skull invaders: when surgical pathology and neuropathology worlds collide

Skull and dura serve as effective barriers to penetration by most tumors, often preventing masses originating intracranially from extending into the contiguous bone and soft tissues, or those arising in head and neck regions from extending into the dura and brain tissue. We review our 15-year experience with extracranial tumors that had sufficiently invaded adjacent skull, dura, or brain from the "outside-in" to require a neurosurgeon to participate in the surgical resection and discuss our 40 cases in context with the literature. Sinonasal-origin tumors (n = 17) and cutaneous tumors (n = 10) were the most frequent skull-invaders. Most of the cutaneous tumor types were squamous cellcarcinomas (n = 9); diverse sinonasal-origin types included 4 squamous cell carcinomas, 4 adenoid cystic carcinomas, 2 sinonasal undifferentiated carcinomas, 2 sinonasal adenocarcinomas, and single examples each of sinonasal-origin hemangiopericytoma, solitary fibrous tumor, melanoma, mucocele, and teratocarcinoma. There were 9olfactory neuroblastomas, and middle ear-origin basal cell carcinoma,recurrent glomus jugulare, and orbital malignant hidradenoma were also seen. Unique tumors included a cutaneous cylindroma invasive of skull convexity occurring in familial cylindromatosis and a ganglioneuroma of the middle ear with massive bilateral skull base extension. Convexity dural spread, a seldom-reported pattern of dissemination, was seen in 1 olfactory neuroblastoma and 1 adenoid cystic carcinoma. The ability to show skull/dural invasion did not correlate with specific histopathologic features; even benign tumor types can show skull/dural penetration.

Extensive central nervous system involvement in Merkel cell carcinoma: a case report and review of the literature

Introduction

Merkel cell carcinoma is a rare malignant cutaneous neoplasm that is locally invasive and frequently metastasizes to lymph nodes, liver, lungs, bone and brain. The incidence of Merkel cell carcinoma has increased in the past three decades.

Case presentation

A 65-year-old Caucasian man presented with a sudden onset of severe headache and a three-month history of balance disturbance. Magnetic resonance imaging revealed a large meningeal metastasis. The radiologic workup showed retroperitoneal and inguinal lymph node metastases. Biopsy of the inguinal lymph nodes showed metastases of Merkel cell carcinoma. Biopsy from three different suspected skin lesions revealed no Merkel cell carcinoma, and the primary site of Merkel cell carcinoma remained unknown. Leptomeningeal metastases, new axillary lymph node metastases, and intraspinal (epidural and intradural) metastases were detected within six, seven and eight months, respectively, from the start of symptoms despite treating the intracranial metastasis with gamma knife and the abdominal metastases with surgical dissection and external radiotherapy. This indicates the aggressive nature of the disease.

Conclusion

To the best of our knowledge, this is the first report in the literature of an intracranial meningeal metastasis of Merkel cell carcinoma treated with gamma knife and of intraspinal intradural metastases of Merkel cell carcinoma. Despite good initial response to radiotherapy, recurrence and occurrence of new metastases are common in Merkel cell carcinoma.

Clinical emergence of neurometastatic merkel cell carcinoma: a surgical case series and literature review

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine neoplasm of possible viral origin and is known for its aggressive behavior. The incidence of MCC has increased in the last 15 years. Merkel cell carcinoma has the potential to metastasize, but rarely involves the central nervous system. Herein, we report three consecutive surgical cases of MCC presenting at a single institution within 1 year. We used intracavitary BCNU wafers (Gliadel^®) in two cases. Pathological features, including CK20 positivity, consistent with MCC, were present in all cases. We found 33 published cases of MCC with CNS involvement. We suggest that the incidence of neurometastatic MCC may be increasing, parallel to the increasing incidence of primary MCC. We propose a role for intracavitary BCNU wafers in the treatment of intra-axial neurometastatic MCC.