Right Atrial Metastatic Melanoma with Unknown Primaries

Abstract

A 54-year-old male with history of anemia and rheumatoid arthritis presented with a three-month history of dyspnea on exertion and lower extremity edema. Patient was referred for a transthoracic echocardiogram that revealed a large right atrial mass with reduced ejection fraction of 40% and an incidental large liver mass. Subsequent cardiac MRI revealed a lobulated right atrial mass measuring 5.4 cm × 5.3 cm with inferior vena cava compression and adjacent multiple large liver lesions confirmed to be malignant melanoma through biopsy. Interestingly, no primaries were found in the patient. PET/CT imaging displayed hypermetabolic masses within the right atrium and liver that likely represent metastases, as well as bilateral pleural effusions, most likely due to heart failure. Preoperative coronary angiogram demonstrated perfusion to the mass by a dense network of neovasculature arising from the mid right coronary artery. The cardiac melanoma was surgically removed, and the right atrium was reconstructed with a pericardial patch. After surgery, all cardiac chambers appeared normal in size and function with associated moderate tricuspid regurgitation. The patient is currently being administered ipilimumab for systemic therapy of metastatic melanoma.

Nerve-associated Schwann cell precursors contribute extracutaneous melanocytes to the heart, inner ear, supraorbital locations and brain meninges

“…These rare neoplasias can be found almost anywhere in the body and are almost impossible to detect early enough for a possible surgical treatment. Interestingly, although extracutaneous melanomas are in most cases considered a metastasis, an increasing number of authors report cases of malignant melanomas revealed inside the heart, on the spinal cord, and in leptomeninges without a primary tumor being identified [91][92][93][94]. The presence of melanomas at the locations that, under normal conditions, host the extracutaneous melanocytes, the absence of identified primary tumor and certain gene expression similarities between melanoma cells and the Schwann cells suggest these extracutaneous melanocytic tumors might be either derived from the recruited Schwann cells in that particular location or directly originate from the extracutaneous melanocytes present physiologically in these locations.…”

Treatment Outcomes for Metastatic Melanoma of Unknown Primary in the New Era: A Single-Institution Study and Review of the Literature

“…None of the papers included in Figure 2b have overlapping patient populations. Of the 24 MUP patients identified, 13 patients (54%) (labeled as L-I1 – L-I13 in Figure 2b) were enrolled on a phase II clinical trial assessing the efficacy of ipilimumab in pretreated stage IV patients, 10 patients (42%) (L-I14 – L-I23) were enrolled on the ipilimumab expanded access program, and 1 patient (4%) (L-I24) was featured in a case report [11–13]. All patients were treated with ipilimumab 3 mg/kg every 3 weeks for 4 planned cycles.…”

Mediastinal Non-Hodgkin's Lymphoma Metastatic to Right Atrium Mimicking Right Atrial Myxoma

“…This case is very rare and often considered an atrial myxoma. It was also found that various tumors can metastasize into the heart, ranging from the most common types, such as bronchogenic carcinoma, malignant melanoma, malignant lymphoma, pancreatic carcinoma, and others (Kuriakose et al 2015, Sweni et al 2019. These metastatic tumors are often misdiagnosed with atrial myxoma.…”