22 March 2007 – Case of the Week #78
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We thank Drs. Ignat Schwartz and Eddie Fridman, The Chaim Sheba Medical Center, Ramat-Gan, Israel, for contributing this case. We invite you to contribute a Case of the Week by emailing [email protected] with microscopic images (any size, we will shrink if necessary) in JPG format, a clinical history, your diagnosis and any other images (gross, immunostains, EM, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US) for your time after we send out the case. Please only send cases with a definitive diagnosis.
Case of the Week #78
A previously healthy 65 year old woman had a left atrial mass approximately 30 cc in volume.
What is your diagnosis?
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Cardiac myxoma with glandular differentiation
The tumor has a focal glandular component with bland columnar cells containing mucinous vacuoles. No cytologic atypia or mitotic activity is present. The stroma is hypocellular, edematous and myxoid, with occasional prominent blood vessels.
Routine stains performed included mucicarmine and Alcian blue (pH 2.5), which highlighted mucinous vacuoles. Immunostains performed included CK7 and MNF-116 (a broad spectrum cytokeratin), which strongly stained the glandular structures. Other positive markers were CAM 5.2, CEA, CA19.9, EMA and CD31. Negative markers included CA 15.3 and CU-18 / BCA-225 (breast cancer tumor markers), CK20, TTF1, chromogranin A, synaptophysin, thyroglobulin and S100.
Myxomas are the most common primary tumor of the heart, although they are still rare. They are distinct from soft tissue myxomas. The mean patient age is 50 years. Ninety percent occur in the atria, with 80% occurring on the left side. They often occur at the fossa ovalis, and may be up to 10 cm in dimension. Cases associated with Carney’s syndrome typically present at a mean age of 24 years (AJSP 1985;9:53).
Myxomas often have a gelatinous surface. The margins may be irregular or smooth. Histologically, myxomas contain complex structures resembling rings or poorly formed glands, composed of stellate or globular (lepedic) cells with abundant eosinophilic cytoplasm and an indistinct cell border. The nuclei are oval with open chromatin and indistinct nuclei. There is a prominent myxoid stroma. Mitotic activity is variable, and often more prominent near the tumor surface.
Tumor cells are immunoreactive for CD31, CD34 and calretinin (AJCP 2000;114:754). Glandular components may be keratin positive, as in this case.
The main differential diagnosis in this case is metastatic carcinoma. It typically has anaplastic tumor cells with prominent mitotic activity. Clinical history may also be helpful. Immunostains are often less helpful, as both tumors may be strongly keratin immunoreactive.
Myxomas are benign, but may cause death via embolization. Excision is curative in most cases, with only rare recurrence or metastases.
Nat Pernick, M.D., President
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