Skeletal muscle choristoma in the lung of a female Sprague-Dawley rat: a case report.

Abstract In this report we describe a choristoma in the lung of a female placebo rat. The lesion was observed microscopically in the central part of the left lung lobe and was characterized by a nodule consisting of well-differentiated skeletal muscle cells. The muscle fibers were haphazardly organized giving the nodule a poorly demarcated border. Choristoma is a very rare lesion.