Congenital adrenal hyperplasia (CAH) refers to group of inherited diseases resulting from impaired adrenal steroidogenesis, and its most common cause is 21-hydroxylase deficiency. Testicular adrenal rest tumors (TARTs) are an important complication of CAH, which probably develop from ectopic remnants of intra-testicular adrenal tissue stimulated by Adrenocorticotropic hormone (ACTH) hypersecretion. These lesions are typically located within the rete testis and are bilateral, synchronous, nodular and multiple. TART usually, but not always, responses to suppressive medical therapy. TART leads to testicular structural damage, spermatogenesis disorders, infertility and most importantly, mass-forming lesions that could be mistaken for Leydig cell tumor (LCT). The later has a significantly different behavior with up to 10% of being malignant. Nowadays, due to advances in diagnosing and treating CAH, mass-forming TART is rarely encountered. As a result, there is the paucity in the medical literature regarding its features from pathological perspective. We herein present a case of mass-forming TART and we discuss the clinical, radiological, and morphological features as well as the major differential diagnosis of this rare lesion.