Transitional cell carcinoma metastasizing to an atrial myxoma

Cardiac myxoma with atypical cell population mimicking malignancy - a diagnostic pitfall

Herein, a case of a 45-year-old woman is reported with left atrial myxoma showing unique histological findings mimicking malignancy. For 3 months before surgery, the patient suffered from a long-standing fever of unknown etiology, malaise and weight loss; she had no history of malignancy. The CT scan revealed a tumorous mass in the left atrium. Grossly, the tumor had a smooth rounded surface with areas of haemorrhage on the cut surface. Microscopic examination revealed two distinct regions. One showed classical myxoma histology, the other atypical and highly cellular population with sarcoma-like or melanoma-like features mixed with inflammatory cells and posthemorrhagic changes. Immunohistochemically, the atypical cells expressed calretinin and CD31, analogous to the neighbouring bland myxoma cells. Negative markers included SOX10, S100, Melan A, HMB45, CD34, desmin, ERG, CK, LCA, CD68 and MDM2; SMARCB1/INI1 was retained. The proliferation index Ki67 was low, in about 1 % of atypical cells. The results suggest exaggerated reactive and degenerative changes of the myxoma cells rather than true malignant transformation. Similar case reports of cardiac myxomas and diagnostic challenges are discussed.

A case of comorbid myxoma and chronic lymphocytic leukemia: not just a coincidence?

Background. It is unclear why cardiac myxomas develop. We describe a case of comorbid myxoma and chronic lymphocytic leukemia (CLL) to offer insights into the tumor's pathophysiology. Case. A 56-year-old female with recurrent venous thromboembolism developed embolic stroke. Transesophageal echocardiogram showed a 1.7 × 1 cm sessile left atrial mass at the interatrial septum. Histopathology revealed myxoma with a B cell lymphocytic infiltrate suggestive of a low grade lymphoproliferative disorder. Bone marrow biopsy and flow cytometry of blood and the cardiac infiltrate supported the diagnosis of atypical CLL. She was followed clinically in the absence of symptoms, organ infiltration, or cytopenia. After eighteen months, she developed cervical and axillary lymphadenopathy. Biopsy confirmed B cell CLL/small lymphocytic lymphoma. She elected to undergo chemotherapy with fludarabine, cyclophosphamide, and rituximab, with clinical remission. Conclusions. The coexistence of two neoplastic processes may be coincidental, but the cumulative likelihood is estimated at 0.002 per billion people per year. A shared pathogenic mechanism is more likely. Possibilities include chronic inflammation, vascular endothelial growth factor A, shared genetic mutations, changes in posttranslational regulation, or alterations in other cellular signaling pathways. Additional studies could expand our current understanding of the molecular biology of both myxomas and CLL.