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Heart - Cyst

Image of cyst in the heart from a male BALB/c mouse in a subchronic study
Heart - Cyst in a male BALB/c mouse from a subchronic study. A cyst is present in the atrial septum (arrow).
Figure 1 of 3
Image of cyst in the heart from a male BALB/c mouse in a subchronic study
Heart - Cyst in a male BALB/c mouse from a subchronic study (higher magnification of Figure 1). Inflammatory cells are present in the tissue around the cyst (arrow).
Figure 2 of 3
Image of cyst in the heart from a male BALB/c mouse in a subchronic study
Heart - Cyst in a male BALB/c mouse from a subchronic study (higher magnification of Figure 1). The cyst is lined by flattened epithelium.
Figure 3 of 3
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comment:

Cysts ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , and Figure 3image opens in a pop-up window ) are defined as epithelium-lined sacs, and in the heart, they are typically located within the atrium or near the interatrial septum. The lining epithelium is typically flattened. Cysts may be the result of a developmental malformation, possibly of thyroglossal duct origin. Cysts should be differentiated from cystic, ectopic thyroid or thymic tissue in the heart.

recommendation:

Heart - Cyst should be diagnosed but should not be graded. The location of this lesion should be described in the pathology narrative. A diagnosis of "Cyst" should be used when the tissue of origin cannot be definitively identified. If the tissue is determined to be of thymic or thyroid origin, a diagnosis of "Heart - Ectopic tissue" is preferred.

references:

Elwell MR, Mahler JF. 1999. Heart, blood vessels, and lymphatics. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 361- 380.