Atrial myxoma

General: Benign. Most often sporadic, but may also be part of the Carney complex (aka NAME: nevi, atrial myxoma, ephelides or LAMB: lentigines, atrial myxoma, blue nevi) in conjunction with abnormal skin pigmentation, cutaneous & cardiac myxomas, and endocrine abnormalities. May clinically cause symptoms of mitral valve stenosis by creating a ball-valve obstructive effect.

Gross: Typically arise in the left atrium near the fossa ovale, but those associated with a familial syndrome are more common in the right atrium. May resemble an atrial thrombus but are usually mobile, attached only by a thin stalk. Usually round-to-oval, but may be elongate or papillary. Generally cured by simple resection, though familial forms may "recur."

Microscopic: Somewhat variable but usually composed of plump, stellate to spindle cells arranged in cords, with primitive vessels, all in a loose, myxoid stroma. The stroma may contain hemorrhage or hemosiderin and variable inflammation. Heterologous glands or EMH may be seen in a minority of cases (~2%), but it is important to distinguish from metastatic adenocarcinoma.

Differential Diagnosis:

• Metastatic adenocarcinoma

Stains:

• Positive: Calretinin, CD31, CD34, variable S100
• Negative: CKC (positive only in heterologous glands)
• Suggested, focused panel:

(Lefkowitch: AP Board Review)

Images:


Cases:

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