Rare Benign Entities of the Breast - Myoid Hamartoma and Capillary Hemangioma

Genetic Characterization of Myoid Hamartoma of the Breast

BACKGROUND/AIM

Myoid hamartoma of the breast is a very rare benign lesion of which only a few cases have been reported. The pathogenesis is unknown and nothing is known about its genetic constitution. We report here the genetic characterization of a myoid hamartoma of the breast.

MATERIALS AND METHODS

Cytogenetic, fluorescence in situ hybridization (FISH), RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), and Sanger sequencing analyses were performed on a myoid hamartoma of the breast.

RESULTS

G-Banding analysis of short-term cultured tumor cells yielded the karyotype 46,XX,t(5;12)(p13;q14)[6]/46,XX[4]. FISH showed rearrangement of the high mobility group AT-hook 2 (HMGA2) gene. RNA sequencing detected fusion of HMGA2 (12q14) with a sequence from 5p13. RT-PCR together with Sanger sequencing verified the HMGA2-fusion transcript.

CONCLUSION

Myoid hamartoma of the breast may be pathogenetically related to benign connective tissue tumors with HMGA2 rearrangements, such as pulmonary hamartomas, lipomas, myolipomas, and leiomyomas.

Mammary myoid hamartomas: reports of two cases and a review of the literature

The purpose of this report is to determine the clinicopathological and immuno-phenotypical characteristics of myoid hamartoma of the breast (MHB). The clinical data, histological morphology, and immunohistochemical results of 2 patients diagnosed with MHB were analyzed, and 15 cases of MHB reported in China were reviewed. Both patients were female, aged 28 and 35 years old, and their lesions were located in the upper outer quadrant of the left breast and the right breast respectively. The lesions measured 3 cm × 3 cm × 2.5 cm and 6.5 cm × 6 cm × 4.5 cm. A gross examination indicated a grayish solid block with clear boundaries. A microscopic examination showed different proportions of ducts and acini, beam myoid cells, adipose tissue, and fibrous stroma. The myoid cell bundles of both specimens were positive for vimentin, SMA, h-caldesmon and desmin, but negative for ER, PR, PCK, s-100, Calponin, and P63. Both cases were confirmed as MHB based on their clinical, histological and immuno-phenotypical characteristics. Our findings provide further insights into the pathological basis of MHB, which can help avoid both misdiagnosis and missed diagnosis.

[Rare benign breast tumors including Abrikossoff tumor (granular cell tumor), erosive adenomatosis of the nipple, cytosteatonecrosis, fibromatosis (desmoid tumor), galactocele, hamartoma, hemangioma, lipoma, juvenile papillomatosis, pseudoangiomatous hyperplasia, and syringomatous adenoma: Guidelines for clinical practice]

OBJECTIVES

To provide guidelines for clinical practice from the French College of Gynaecologists and Obstetricians (CNGOF), based on the best evidence available, concerning rare benign breast tumors: Abrikossoff (granular cell tumor), erosive adenomatosis of the nipple, cytosteatonecrosis, fibromatosis (desmoid tumor), galactocele, hamartoma, hemangioma, lipoma, juvenile papillomatosis, pseudoangiomatous hyperplasia, and syringomatous adenoma.

METHODS

Bibliographical search in French and English languages by consultation of Pubmed, Cochrane and international databases.

RESULTS

For erosive adenomatosis of the nipple, surgical excision is recommended to exclude Paget's disease or cancer (grade C). When surgery is performed for breast desmoid tumor or syringomatous adenoma, free margins are recommended (grade C). Without clinico-radio-histologic discordance, surgical abstention may be proposed for Abrikossoff tumor (granular cell tumor), cytosteatonecrosis, galactocele, hamartoma, hemangioma, lipoma, juvenile papillomatosis, pseudoangiomatous hyperplasia, and syringomatous adenoma (grade C).