a 72-year - old woman presented for further examination of a right breast lump . according to the patient , the lump had been present for at least 10 years . she complained of discomfort of recent onset in the right breast . on physical examination , a soft , mobile , 10 cm mass , which occupied nearly the entire right breast , was palpated . on mammography , a large circumscribed mass surrounded by a water - density capsule the mass was a mixture of isodense and fat densities and had dystrophic calcifications in a branching pattern . 1a , b ) . on ultrasonography ( us ) , the mass was very heterogeneous and completely encompassed in a thin echogenic pseuduocapsule of compressed breast tissue , which was compatible with hamartoma . however , a careful us examination revealed an irregular hypoechoic mass of 1.4 cm with a non - parallel orientation within the hamartoma ( fig . 1c ) . a retrospective review of the mammograms revealed focal asymmetry , which correlated with the suspicious mass on us ( fig . 1a , b ) . the lesion was early enhanced and a washout on enhanced mri scans ( fig . surgical excision for entire mass was done and the diagnosis from the frozen specimen of the suspicious area was idc . , there was no evidence of local recurrence of the idc or any distant metastasis . mammary hamartomas , a term applied to breast tumors in 1971 by arrigoni et al . ( 13 ) , have also been referred to as lipofibroadenomas , adenolipofibromas , and fibroadenolipomas ( 1 ) . hamartomas may present as tender or non - tender palpable lumps , but are often discovered incidentally during a screening mammography ( 1 , 14 ) . the typical mammographic feature of hamartomas is a circumscribed fibrofatty mass ( 15 ) . on us , most mammary hamartomas have circumscribed margins , an oval shape , and heterogeneous internal echogenicity ( 16 , 17 ) . the clinical , radiologic , and histologic findings of the previously described 14 cases of malignant hamartomas and the current case are summarized in table 1 . the mean patient age was 56.3 years ( range , 25 - 78 years ) . the size of the hamartomas range from 1.5 - 12.0 cm in diameter and the size of the associated carcinomas range from 0.3 - 3.5 cm in diameter . of the described 15 cases , mammography was obtained in 12 cases , of which 10 showed the typical appearance of hamartomas with suspicious features , such as clusters of microcalcifications , pleomorphic micocalcifications , and spiculated masses . the remaining two cases had the typical appearance of a hamartoma with no suspicious features , thus co - existing malignancies were unexpected findings at the time of tumorectomy . us findings were available in only six cases , of which four had suspicious masses with irregular margins , hypoechogenicity , or a non parallel orientation within the hamartomas ; and two cases were diagnosed pre - operatively as carcinomas by us - guided fine needle aspiration or core needle biopsies and underwent one - step curative surgery ( 6 , 7 ) . as stated above , the majority of cases had suspicious findings within the hamartoma on mammography or us . radiologists therefore need to pay careful attention in order to detect subtle suspicious findings , even though mammography or us may show typical hamartomas . among the 15 cases described here , 12 had carcinomas that were confined to the hamartomas and the remaining three cases had carcinomas that involved both the hamartomas and adjacent normal breast tissue . if carcinomas involve both the hamartoma and normal breast tissue , it is difficult to determine whether the carcinoma arises within the hamartoma or an isolated carcinoma which initiates growth nearby later extends into the hamartoma . however , in the majority of cases described here , including the current case , the carcinomas were located within the hamartomas , ( 2 - 5 , 7 , 8 , 10 - 12 ) thus we believe that the malignancies arose within the hamartomas . in conclusion , breast hamartomas have generally been classified as rare , benign tumors , and carcinomas occur only rarely . radiologists should recognize that malignancy may co - exist or develop in hamartomas and be alert to the presence of suspicious features within a hamartoma .