Signet-ring cell melanoma of the gastroesophageal junction: a case report and literature review

Melanoma metastasis mimicking gastric cancer: a challenge that starts from diagnosis

The gastrointestinal tract is an uncommon site of metastasis in melanoma. However, when the primary melanoma cannot be found, the diagnosis of gastric melanoma by endoscopic biopsy is problematic mainly because some tumors are amelanotic and do not contain melanin granules detectable by microscopy. A 56-year-old Caucasian man with melanoma was referred to us following an initial histopathological diagnosis via gastroscopy of poorly differentiated primary gastric carcinoma. A computerized tomography (CT) scan showed metastatic disease and on the basis of this information we started palliative chemotherapy. However, the atypical presentation of the disease with subcutaneous metastases prompted us to make a more in-depth evaluation. Immunohistochemical evaluation modified the diagnosis to melanoma. After only one cycle of chemotherapy, treatment was changed to dabrafenib + trametinib, which was better tolerated and initially induced a partial response. The patient is currently in good clinical condition 20 months after diagnosis. Our case report highlights the difficulty in diagnosing melanoma of the gastrointestinal tract and indicates the need for pathologists and clinicians to consider such a possibility when they are faced with a diagnosis of poorly differentiated gastric cancer and unusual sites of metastasis.

Primary gastric melanoma in adult population: a systematic review of the literature

BACKGROUND

Primary gastric melanoma (PGM) is a rare malignant tumour of the stomach with poor prognosis. The aim of this systematic review was to assess the available literature on this entity and to highlight its biological behaviour and preferred treatment approach.

METHODS

PubMed and Cochrane bibliographical databases were independently searched (last search: 2 February 2020) by two investigators for articles reporting on PGM in the adult population.

RESULTS

Twenty-five studies met the inclusion criteria and concerned collectively 25 patients (18 males and seven females) with an age of 63.4 ± 8.97 years (mean ± standard deviation). Main symptoms included abdominal pain (64%), weight loss (48%) and hematemesis or melena (32%). The most frequent tumour location was the body of the stomach (54.2%). All tumours were surgically resected and the majority of the patients had a partial gastrectomy (52%). Median recurrence time was 5 months and 12% of patients reached 5-year survival landmark.

CONCLUSION

PGM is a rare disease characterized by an aggressive malignant behaviour. Its differential diagnosis from a metastatic lesion is crucial. A prompt diagnosis and therapeutic approach are needed. Further studies are required to elucidate the optimal management of this clinical entity.

Case Report: Primary melanoma of the gastroesophageal junction

Primary malignant melanoma represents the fifth most common cancer in the United States. It is subdivided into two forms: cutaneous (90%), visceral (8%, including ocular and mucosal) and of unknown primary (2%). The vast majority of gastrointestinal melanomas are secondary lesions until proven otherwise. Primary esophageal melanoma in particular is exceedingly rare, less than 200 cases have been documented in the literature to date. It is highly prevalent in Japan and occurs twice as much in men than women around the 6th decade of life. It has a predilection for the middle and lower esophagus, with only 6 cases occurring at the gastroesophageal junction worldwide. Its etiology and pathogenesis are poorly understood, and no curative treatment has been established given the paucity of cases. We present a case of primary melanoma of the gastroesophageal junction which represents the 2nd incident case in the united states and 7th worldwide.

Amelanotic Signet Ring Cell Melanoma Presenting as Breast Lump- A Diagnostic Conundrum

Amelanotic signet ring cell melanoma is one of the rare variants of malignant melanoma. Here we are presenting a case of a 58-year-old female with chief complaints of swelling in the left sternal region/breast, and right cervical region. Contrast Enhanced CT scan showed the two well circumscribed lobular mass lesions with central necrosis in the left breast. The radiologist opined the lesions as intramammary nodes. Biopsy from the larger breast mass lesion showed a tumour with cells arranged in discohesive pattern less with hetrogenos morphology. These tumour cells had a predominantly signet ring morphology along with markedly pleomorphic tumour cells and giant cells. These tumour cells were negative for pan CK and positive for S100, HMB45. So the case was diagnosed as metastatic amelanotic malignant melanoma with signet ring morphology.

Primary gastric melanoma: case report of a rare malignancy

We report the case of a 64-year-old white male who presented to his primary care physician with complaints of fatigue. Physical exam was unremarkable and laboratory studies revealed profound anemia, for which the patient received a transfusion. Esophagogastroduodenoscopy revealed a bleeding mass in the proximal stomach that was histologically determined to be malignant melanoma, with immunohistochemical staining demonstrating positivity for SOX10, S100, MART-1, and HMG-45. After an extensive dermatological exam no other primary lesion was identified. Whole body positron emission tomography (18-FDG-PET/CT) demonstrated pathologic uptake only in the area of the proximal stomach. For this reason, primary gastric melanoma was suspected in this patient. The patient underwent subtotal gastrectomy with mass excision followed by Roux-en-Y reconstruction. Very few cases of primary gastric melanoma have been reported. We report this case and present diagnostic criteria for primary non-cutaneous melanoma and discuss potential non-surgical therapies.

Mesothelioma with signet-ring cell features: report of 23 cases

Signet-ring cell mesothelioma is uncommon and only two case reports have been published on this mesothelioma variant, both of which were initially misdiagnosed as signet-ring cell carcinoma. Herein are reported 23 signet-ring cell mesotheliomas that were investigated by immunohistochemistry, 12 of which were also studied by electron microscopy. Twenty-one of the cases originated in the pleura and two in the peritoneum. For comparison purposes and in order to determine the value of these techniques in the differential diagnosis of these tumors, seven cases of signet-ring cell lung adenocarcinoma were also studied. All signet-ring cell mesotheliomas were positive for calretinin, keratin 5/6, keratin 7, and mesothelin, 93% for podoplanin, and 91% for WT1; whereas, none reacted for MOC-31, CEA, TAG-72, CD15, TTF-1, napsin A, or CDX2. Among signet-ring cell lung adenocarcinomas, 100% were positive for keratin 7, CEA, and napsin A, 86% each for TTF-1 and TAG-72, 71% for CD15, and 14% for mesothelin, while all were negative for calretinin, keratin 5/6, WT1, podoplanin, and CDX2. After analyzing the results, it is concluded that the panels of markers used in the differential diagnosis of this mesothelioma variant should include those markers that are usually expressed in mesotheliomas (eg, calretinin, keratin 5/6, WT1, and podoplanin), broad-spectrum carcinoma markers that are frequently expressed in adenocarcinomas regardless of their site of origin (eg, MOC-31 and CEA), and organ-associated markers (eg, TTF-1 and napsin A for lung), which allow the site of origin of a metastatic adenocarcinoma to be established. Electron microscopy can be very useful as it permits the identification of characteristic ultrastructural mesothelioma and adenocarcinoma markers, and it also allows a better understanding of the morphologic features seen on routine light microscopy. Pathologists should be aware of this mesothelioma subtype as it can potentially be confused with other tumors that exhibit signet-ring features.