Review of Merkel cell carcinoma with solitary pancreatic metastases mimicking primary neuroendocrine tumor of the pancreas

OBJECTIVE/BACKGROUND

Merkel cell carcinoma (MCC) but metastases to the pancreas are very rare. There are only a few cases of isolated metastases of MCC to the pancreas. Because of this rarity, it can be wrongly diagnosed as a neuroendocrine tumor of the pancreas(pNET), especially the poorly differentiated neuroendocrine carcinoma (PNEC) subtype, in which the treatment is vastly different than that of MCC with isolated metastases of the pancreas.

METHODS

An electronic search of the PubMed and google scholar databases was performed to obtain the literature on MCC with pancreatic metastases, using the following search terms: Merkel cell carcinoma, pancreas, and metastases. Results are limited to the following available article types: case reports and case series. We identified 45 cases of MCC with pancreatic metastases from the PubMed and Google Scholar database search and examined their potential relevance. Only 22 cases with isolated pancreatic metastases were taken for review including one case that we encountered.

RESULTS

The results from our review of cases of isolated pancreatic metastases of MCC were compared to the characteristics of the poorly differentiated pancreatic neuroendocrine tumor (PNEC). We found the following: (a) MCC with isolated pancreatic metastases occurred at an older age than PNEC and with male gender predominance (b) Most of the metastases occurred within 2 years of initial diagnosis of MCC (c) Resection of pancreatic mass was the first line treatment in case of resectable PNECs whereas resection of metastases was infrequently performed in MCC with pancreatic metastases.

Comments on and Illustrations of the EFSUMB CEUS Guidelines: Transabdominal and Endoscopic Ultrasound Features of Intrapancreatic Metastases and the Role of Multiparametric Imaging and EUS-Guided Sampling in Rare Pancreatic Tumors

A definite pathologic diagnosis of intrapancreatic metastasis is crucial for the management decision, i.e., curative or palliative surgery versus chemotherapy or conservative/palliative therapy. This review focuses on the appearance of intrapancreatic metastases on native and contrast-enhanced transabdominal ultrasound and endoscopic ultrasound. Differences and similarities in relation to the primary tumor, and the differential diagnosis from pancreatic carcinoma and neuroendocrine neoplasms are described. The frequency of intrapancreatic metastases in autopsy studies and surgical resection studies will be discussed. Further emphasis is placed on endoscopic ultrasound-guided sampling to confirm the diagnosis.

Merkel Cell Carcinoma With Isolated Pancreatic Metastasis

Merkel cell carcinoma (MCC) is a highly aggressive cutaneous neuroendocrine carcinoma, frequently associated with distant metastasis. However, recurrence of MCC manifesting with only pancreatic involvement is exceedingly rare. A 53-year-old man presented to our institution with abdominal discomfort 3 months after initial resection of chest wall MCC. Imaging revealed lesions in the pancreas and peripancreatic lymph nodes. Pathology obtained through endoscopic ultrasound confirmed recurrence of MCC. He underwent chemotherapy with cisplatin and etoposide, resulting in a complete resolution of the pancreatic lesions. Unfortunately, he passed away from sudden cardiac arrest while being in remission from MCC. Immunohistochemistry is crucial in differentiating MCC from primary pancreatic glandular and neuroendocrine tumors. While there are no definitive guidelines in the management of pancreatic lesions associated with MCC, checkpoint inhibitor immunotherapy is increasingly being used.

Evaluation of metastases to the pancreas with fine needle aspiration: A case series from a single centre with review of the literature

OBJECTIVE

Fine needle aspiration (FNA) is a minimally invasive albeit highly effective modality used to detect solid and cystic pancreatic lesions. This manuscript aims to present our experience in diagnosing metastases to the pancreas and highlight the importance of immunocytochemistry in the diagnostic process. It also aims to provide a brief review of the literature on this topic.

METHODS

We retrospectively searched our archives for cases of metastatic deposits to the pancreas diagnosed with FNA over a 5-year period. We also reviewed the literature for such cases.

RESULTS

We describe seven cases from our archives that metastasised to the pancreas. Three of them (43%) represented metastatic renal cell carcinoma while the rest four comprised deposits from a lung adenocarcinoma, a colon adenocarcinoma, an adrenal leiomyosarcoma, and a small cell carcinoma of the urinary bladder, respectively. History of primary malignancy was available for all seven patients. All diagnoses were confirmed with the use of immunostains. In our literature review, similar to our case series, renal cell carcinoma was the most common metastasis to the pancreas managed with FNA (around one out of three patients; 35%). Of interest, our endoscopic ultrasound-FNA case of pancreatic metastasis from urinary bladder small cell carcinoma is the first reported.

CONCLUSIONS

As metastases to the pancreas are commonly accompanied by diverse prognostic signatures and management strategies compared to primary pancreatic malignancies, their accurate identification is imperative. Pancreatic FNA is a diagnostic modality that can confirm or exclude metastasis to the organ, especially when immunocytochemistry is applied.

Recurrent Merkel cell carcinoma of the gluteal region: A case report

Merkel cell carcinoma (MCC) is a rare malignant tumor of the skin. The development of MCC on non-sun-exposed skin is extremely rare, with few cases reported in the literature. The present authors aimed to highlight the characteristic features and treatment options of this tumor. The present authors present a 50-year-old man who developed MCC on the left gluteal region (non-sun-exposed skin). After surgery with clear margins, adjuvant radiotherapy was given. Three months after radiotherapy, lymphatic recurrence was observed and he was treated with chemotherapy. On follow-up, systemic metastases were found and palliative treatment was planned.

The diagnostic utility of Merkel cell polyomavirus immunohistochemistry in a fine needle aspirate of metastatic Merkel cell carcinoma of unknown primary to the pancreas

Merkel cell carcinoma (MCC) is an aggressive skin tumor with a high tendency for metastases. We report a case of MCC initially presenting as axillary and pancreatic metastases. A 33-year-old HIV-positive Hispanic male presented with a history of a rapidly growing axillary mass. A needle core biopsy demonstrated an epithelioid neoplasm composed of small to medium-sized cells with high nuclear-cytoplasmic ratio, nuclear molding, and frequent mitotic figures. A subsequent PET scan revealed a 1.5 cm FDG avid mass in the pancreas. Endoscopic ultrasound-guided FNA of the pancreatic mass showed neoplastic cells with similar morphology to those of the axillary mass. The tumor cells were positive with pancytokeratin AE1/AE3, CK20, CD56, synatophysin, chromogranin, and Merkel cell polyomavirus (MCPyV). This case of MCC most likely originated from a resolved primary skin lesion drained by the involved axillary lymph node with subsequent metastases to the pancreas and distant lymph nodes.

EUS-FNA of the Merkel cell carcinoma metastasis to the pancreas: Cytomorphology and immunocytochemistry on direct cytological smears

OBJECTIVE

To report two cases of Merkel cell carcinoma (MCC) metastatic to the pancreas diagnosed with endoscopic ultrasound-guided-fine needle aspiration (EUS-FNA) and to add the case of concomitant chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) and MCC to the literature. The aim is to alert the cytopathologists once more to the problems of differential diagnosis of pancreatic metastasis of MCC and to describe the possibilities of ancillary methods performed on direct cytological smears.

METHODS

EUS-FNA procedures were performed according to standard institution protocol, using 22-G needles with cytopathologist on-site. Based on rapid on-site evaluation (ROSE), additional passes were made for immunocytochemistry (ICC). A mini panel of antibodies was used to aid the differential diagnosis.

RESULTS

Smears revealed a dispersed pattern of small round cells with scant cytoplasm, round nuclei with inconspicuous nucleoli and occasional nuclear moulding, suspicious of small cell carcinoma. Results of ICC applied to the direct cytological smears were as follows: LCA negative, Cytokeratin (clone MNF116) positive, TTF-1 negative, CD 56 positive, NSE weakly positive, Chromogranin A weakly positive and CK20 positive, in one case in a dot-like perinuclear pattern. The diagnosis of MCC was made.

CONCLUSION

Increasing incidence of MCC warrants the inclusion of MCC in the differential diagnosis of tumours of small round blue cell morphology even in unusual sites. The cytomorphological features coupled with an ICC panel are usually enough to make a confident diagnosis of MCC. EUS-FNA is a minimally invasive technique which enables sampling adequate tissue for all the ancillary methods eventually needed to support the diagnosis.

Primary retroperitoneal Merkel cell carcinoma: Case report and literature review

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma that affects elderly patients and typically arises in sun-exposed skin. The disease is very rare and only few cases present with no apparent skin lesion. In the retroperitoneum there are only two cases reported in the literature.

CASE PRESENTATION

We report a case of a 54-year-old Mexican male with MCC, which presented as a large retroperitoneal mass. Pathological and immunohistochemical analysis of the transabdominal CT-guided biopsy specimen revealed a MCC. The patient underwent preoperative chemotherapy followed by a laparotomy and the mass was successfully excised.

DISCUSSION

There are two possible explanations for what occurred in our patient. The most plausible theory is the retroperitoneal mass could be a massively enlarged lymph node where precursor cells became neoplastic. This would be consistent with a presumptive diagnosis of primary nodal disease. Moreover, metastasis to the retroperitoneal lymph nodes has been reported as relatively common when compared to other sites such as liver, bone, brain and skin. The less probable theory is the non-described "regression" phenomena of a cutaneous MCC, but we are not found a primary skin lesion.

CONCLUSION

Preoperative chemotherapy and excision of the primary tumor is the surgical treatment of choice for retroperitoneal MCC. We propose that further studies are needed to elucidate the true efficacy of chemotherapy in conventional and unconventional patients with MCC.

A case series and literature review of Merkel cell carcinoma metastasizing to pancreas

BACKGROUND

Merkel cell carcinoma is a rare aggressive tumor arising from the mechanoreceptors of the epidermis with a relative higher mortality rate stage for stage than melanoma. Microscopically, the cells appear similar to small cell lung cancer, but they specifically stain positive for CK20 and are negative for TTF-1. It is rarely known to metastasize to the pancreas.

AIMS

To report four cases of Merkel cell carcinoma metastasizing to pancreas and compare them to previously reported patients.

METHODS

We performed a retrospective review of all patients who underwent endoscopic ultrasound with fine-needle aspiration (EUS-FNA) for a suspected pancreatic lesion between January 2004 and December 2012. We reviewed other reported cases with a literature search using PubMed, Embase, and Scopus.

RESULTS

Four male patients with mean age of 66 years were found to have metastatic disease in the pancreas on average 29 months after initial diagnosis of MCC. Two cases were diagnosed with EUS-FNA and two with PET-CT. Three patients had multifocal pancreatic involvement which has not been previously described. All four patients died within 3-9 months following tumor spread to the pancreas. Merkel cell carcinoma rarely metastasizes to the pancreas with only 10 cases being described in the medical literature.

CONCLUSIONS

EUS-FNA is an effective tool that can be utilized in diagnosing pancreatic masses. Differentiating metastatic pancreatic tumors, especially Merkel cell carcinoma from primary pancreatic tumor is useful as systemic therapy is an option in pancreatic adenocarcinoma, but is ineffective in metastatic Merkel cell carcinoma.

Solid tumor metastases to the pancreas diagnosed by FNA: A single-institution experience and review of the literature

BACKGROUND

Pancreatic fine-needle aspiration (FNA) is useful for diagnosing pancreatic masses. This article describes the experience of a single institution with metastases to the pancreas sampled by FNA and provides a review of the literature.

METHODS

Medical records were retrospectively searched for pancreatic FNA that showed metastatic disease. Data were gathered for the tumor size, focality, and time period between the primary tumor and the metastasis. A literature search using PubMed was performed.

RESULTS

Pancreatic FNA was performed 2327 times in 14 years at the authors' institution. Twenty-two cases showed metastatic disease. The average size of the metastatic lesions in their greatest dimension was 3.7 cm (range, 1.5-6.5 cm). The majority of the tumors were unifocal (16 of 22 or 73%). A rapid onsite adequacy evaluation was performed for 13 patients (4 were diagnostic of metastasis, 3 were positive for malignant cells, 6 were atypical, and none were negative). There were 14 renal cell carcinomas, 2 colonic adenocarcinomas, 1 urothelial carcinoma, 1 non-small cell lung carcinoma, 1 ovarian serous carcinoma, 1 prostatic adenocarcinoma, 1 papillary thyroid carcinoma, and 1 mesenchymal chondrosarcoma. The median time between the diagnosis of the primary tumor and the initial pancreatic metastasis was 9 years (range, concurrent diagnosis to 21 years). A literature review yielded 12 case series with a variety of metastases to the pancreas diagnosed by FNA and surgical pathology specimens.

CONCLUSIONS

In agreement with prior series, the most common metastasis to the pancreas was renal cell carcinoma. A variety of other primary malignancies were also documented in this study and in the literature. Also, this article reports the first case of metastatic mesenchymal chondrosarcoma to the pancreas diagnosed by FNA.

Metastatic Merkel cell carcinoma (MCC) of pancreas and breast: a unique case

Merkel cell carcinoma (MCC) is a rare potentially fatal skin tumor affecting older and immunosuppressed individuals. It is highly malignant with high rates of metastasis and poor survival.

We present a case of a 67-year-old woman with a palpable mass in the upper abdomen. An abdominal CT revealed a mass in the tail of the pancreas. Two weeks before, lumpectomy of a 3.5 cm tumor of the left breast had been performed. Histology showed a primary neuroendocrine carcinoma of the mammary gland. The patient’s medical history was significant for a 0.7 × 0.9 cm MCC removed from her left forearm 2.5 years ago. There was no evidence of vascular involvement or peritoneal disease and by all criteria was resectable. A somatostatin receptor scintigraphy showed an enhanced uptake in the pancreatic tail region. The tumor was immunohistochemically strong staining for synaptophysin and CD56. The diagnosis of a metastatic-MCC in the tail of the pancreas was made. Further histological investigation of the prior removed neuroendocrine breast tumor and the MCC of the left forearm confirmed neuroendocrine origin and identical histology to the previously resected MCC of the left forearm. In this article, we aim to highlight that MCC has the potential to spread even in unusual organs, such as pancreas or breast, and therefore a diligent follow-up should be applied in patients with MCC.

Imaging in patients with merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor of the skin with a mortality rate of approximately 25% (Peloschek et al., 2010). Accurate assessment of nodal involvement in patients with MCC predicts significantly overall outcome (Smith et al., 2012 and Ortin-Perez et al., 2007). Due to the rarity of this highly aggressive disease, only a few imaging reports on MCC were published, and subsequently still to date no accepted imaging algorithm for MCC is available. For primary staging of MCC, general recommendations have included ultrasonography, chest X-ray CT, and MRI, but recent articles show that the use of sentinel node and FDG-PET/PET-CT is gaining more and more importance.