Primary thymic cholesteroloma: a clinicopathological correlation of four cases of an unusual benign lesion

Four cases of an unusual thymic lesion characterized by the presence of extensive cholesterol cleft granulomata are presented. The patients were four men between the ages of 58 and 71 years (average 64.5 years). The anterior mediastinal masses were discovered during radiological evaluation, in one patient for cardiac disease and one for Barrett’s esophagus. Another patient was symptomatic with cough and dyspnea while the fourth was asymptomatic and the lesion was discovered during routine chest imaging. Complete surgical resection was performed in all four patients. The resected lesions were described as tumor-like masses measuring between 2 and 6 cm in greatest diameter. Histologically, all cases showed identical features, mainly the presence of cholesterol cleft granulomata in an alveolar-like growth pattern. Foreign body-type giant cells and an inflammatory reaction were identified in all cases as well as the presence of remnants of thymic tissue. Clinical follow-up in these patients showed that all are alive and well without evidence of recurrence. The current cases highlight an unusual tumoral thymic lesion that can be clinically confused for an aggressive tumor and that will require complete surgical resection for definitive diagnosis.