We present various male breast lesions including benign (myofibroblastoma, borderline phyllodes tumor which mimicking inflammation, gynecomastia, pseudogynecomastia, epidermal inclusion cyst), infection (abscess, tuberculosis, chronic inflammation), malignancy (invasive ductal carcinoma, ductal carcinoma in situ, mucinous carcinoma) with US, mammography, CT and PET/CT. Pathognomonic histologic and surgical findings of each cases are also provided.

Anatomy The borders of the breast - Superior border : The second rib - Inferior border: The sixth rib - Medial border : Sternum - Lateral border: The midaxillary line The male breast tissue (Fig. 1) - Mirrors the female breast at birth - Peripubertal period ▷ Female : Proliferative effect of estrogen → Female ducts and stroma proliferation ▷Male : Androgenic antagonistic effects → Involution and atrophy of ducts and stroma → Fat makes up most of the breast volume, with few residual ducts...

Benign male breast disease Gynecomastia Most common breast disease in men Nonneoplastic hyperplasia of the ductal and stromal elements of malbe breast in resoponse to hormonal stinulation Causes - Estrogen effects : Neonates, adolescents and the elderly - Endocrine and hormonal disorders : Klinefelter's syndrome, neoplasms, drug use, systemic disease, obesity and medication use Clinical manifestations - A palpable abnormlaity, focal breast tenderness, or a subjective burning senssation - Unilateral or bilateral - Usually subareolar in location Three patterns, based on the mammography findings. -...

The exact knowledge of imaging and pathological features of male breast lesions may aid in narrow of the differential diagnosis.

Nguyen, C., et al., Male Breast Disease: Pictorial Review with Radiologic-Pathologic Correlation. RadioGraphics, 2013. 33(3): p. 763-779. Iuanow, E., M. Kettler, and P.J. Slanetz, Spectrum of disease in the male breast. AJR Am J Roentgenol, 2011. 196(3): p. W247-59.