Giant Mammary Hamartoma Diagnosed by Stereomicroscopic Analysis of the Mammary Glandular Tree in an Adolescent Girl: Report of a Case

Abstract

This report describes a rare case of a giant hamartoma that developed in the right breast of a 17-year-old girl. No abnormalities were found by endocrinological studies and a well-circumscribed tumor, approximately 20 cm in diameter, was easily enucleated without bleeding during surgery, following which the bilateral breasts became nearly symmetrical. Histologic features revealed predominant fibrous stroma and scattered normal or occasionally dysplastic mammary glands without neoplastic properties. No distorted lobular structures indicating fibroadenoma characteristics were observed. Subgross and stereomicroscopic analysis of serial 2-mm-thick sections revealed mature normal lobules and predominant fibrous interstitial components. Therefore, the tumor was diagnosed as a giant hamartoma of the breast, according to the histologically non-neoplastic features and the delimited macroscopic appearance. This is a rare mammary gland disease characterized by the fact that although each of the histological components seemed to be normal, their constitution was abnormal. It appears that not only histological features but also clinical details are indispensable for the diagnosis of this disease.

Hamartoma of the breast

“…First described by Arrigoni et al 12 in 1971, mammary hamartomas were reported to comprise 0.7% of all benign tumours of the female breast 7 . They often present as painless mobile breast lumps in middle‐aged women 4,8,11 . Up to 66% of these lesions are soft and non‐palpable 1,4 .…”

“…7 They often present as painless mobile breast lumps in middle-aged women. 4,8,11 Up to 66% of these lesions are soft and non-palpable. 1,4 These lesions may go unrecognized by the pathologists because they show all the constituents of normal breast tissue and may be reported as 'no pathological diagnosis' or 'normal breast tissue', which are inappropriate diagnoses for a lesion that presents as a palpable and a well-circumscribed mass.…”

“…More common types include fibrous, fibrocystic and fibroadenomatous tissue with varying amounts of adipose tissue. Less frequent types are myoid (muscular) and chondroid (cartilage) hamartomas 9–11 . As the microscopic features of hamartoma are similar to those of other related benign lesions of the breast, diagnosis may be difficult by histological examination alone; in addition, knowledge of radiological, surgical and clinical findings may be required 1…”