A Case of Primary Gastric Melanoma Exhibiting a Rare BRAF V600R Mutation

The Development and Validation of a Nomogram for Predicting Cancer-Specific Survival and a Risk Stratification System for Patients with Primary Gastrointestinal Melanoma

BACKGROUND/AIMS

The aim of our study was to develop and validate a nomogram to predict cancer-specific survival and make a risk stratification system for primary gastrointestinal melanoma.

MATERIALS AND METHODS

Patients with primary gastrointestinal melanoma in the Surveillance, Epidemiology, and End Results database between 2000 and 2018 were included and randomly divided into the training and validation cohort (8:2). A prediction nomogram of cancer-specific survival was constructed based on the risk factors identified in the multivariate Cox regression. Calibration curve, time-dependent receiver operating characteristic, and decision curve analysis were performed. Further, a risk stratification system was developed based on the nomogram.

RESULTS

A total of 433 patients were included. The nomogram was constructed based on age, site, and tumor size, Surveillance, Epidemiology, and End Results (SEER) stage, and therapy. The area under the curves of the nomogram predicting 6-, 12-, and 18-month cancer-specific survival were 0.789, 0.757, and 0.726 for the internal validation and 0.796, 0.763, and 0.795 for the external validation. Calibration curves and decision curve analysis were performed. Further, patients were divided into 2 risk subgroups. The Kaplan-Meier analysis and the log-rank test showed that the risk stratification made well differentiation of patients with different risks of cancerspecific survival.

CONCLUSION

We developed and validated a practical prediction model of cancer-specific survival and a risk stratification system for patients with primary gastrointestinal melanoma, which might be available in clinical practices.

A rare gastrointestinal tumor: primary gastric melanoma

Primary gastric melanoma is an exceptional tumour with less than 20 cases described in the literature, as its origin is not entirely clear as the presence of melanocytes in the stomach has not been demonstrated. Symptomatology is non-specific, which prevents its early detection, and it is diagnosed in late stages. We present the case of a patient who was admitted to our hospital for vomiting in coffee grounds with analytical and haemodynamic repercussions. Urgent gastroscopy revealed a gastric lesion suspicious for malignancy, which was histologically confirmed as gastric melanoma. The therapeutic approach to these tumours is complex and they have a very poor prognosis.

Primary Gastric Malignant Melanoma in a 68-Year-Old Woman: A Case Report and Review of the Literature

Non-cutaneous melanoma is a very rare clinical entity. Gastric melanoma can be primary or secondary, but determining their nature is in most cases very challenging. To date, very few cases of primary gastric melanoma have been described in the literature. We report the first case of primary gastric melanoma documented in a Romanian patient, confirmed through clinical, imagistic, and pathological diagnosis. A 68-year-old female patient presented to our hospital with complaints of dyspepsia, abdominal pain, and weight loss. Esophagogastroduodenoscopy revealed two large sessile masses in the gastric fundus, which was histologically compatible with melanoma; immunohistochemistry staining was positive for vimentin, S100 protein, HMB45 antibody and Melan A/MART1, and negative for pan-CKAE1/AE3, leukocyte common antigen and DOG1. Extensive dermatological and ophthalmological examinations did not identify a primary lesion. The patient was therefore diagnosed with primary melanoma of the stomach. At the time of the diagnosis, multiple bone and pulmonary metastases were detected and considering the poor general status of the patient, surgery was not recommended. She died three months following diagnosis. A review of the literature identified only 32 other reported cases of primary gastric melanoma, all in individuals ≥50 years of age and most of them in male patients. Partial or total gastrectomy was the usual treatment of choice, but prognosis was overall poor. Awareness of this rare condition must be increased among healthcare providers, as early detection can improve survival chances.

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 Malignant Melanoma

Primary gastric malignant melanoma (PGMM) is an extremely rare clinical entity, and few cases have been described in the literature. Here, we report a histologically confirmed PGMM case of a 74-year-old man with a mass in the stomach found by gastroscopy. The patient had no history of melanoma. This rare disease may be misdiagnosed for another gastric malignant tumor type when there is no known primary lesion. Early detection and surgical intervention are critical for long term survival or cure, though the tumor is often advanced at the time of diagnosis and is associated with a dismal outcome.

The challenge of primary gastric melanoma: a systematic review

AIM

Primary gastric melanoma is a rare clinical presentation. The purpose of this review was to compare the 1-year survival in patients who underwent surgery with patients who did not receive treatment.

PATIENTS & METHODS

A systematic search of databases for case reports and case series of primary gastric melanoma was conducted.

RESULTS

The mean survival of patients was 22 months. One-year survival was 56.5% with surgery, rising to 66% with adjuvant therapy. Mean survival of the surgical group was 21.05 months (±20.2) versus 4.5 months (±3.61) in the nonsurgical group.

CONCLUSION

Primary gastric melanoma has a poor prognosis but early surgical intervention can have a significant impact on patient outcome. We reviewed the biology and clinical diagnosis of gastrointestinal melanoma and the current management options available.