CASE 16978 Published on 26.08.2020

Intramammary Myofibroblastoma in a male: A case report

Section

Breast imaging

Case Type

Clinical Cases

Authors

Dr. Sonali Sharma, Dr. Jyoti Arora, Dr. Vidhi Bakshi

Department of Radiology and Nuclear medicine, MEDANTA, The Medicity, Gurugram, Haryana, India

Patient

46 years, male

Categories
Area of Interest Breast ; Imaging Technique Mammography, MR
Clinical History

A 46-year-old male presented with a palpable left breast lump in the upper outer quadrant, present for the last two years with recent-onset local tenderness. On Physical Examination the lump was partly mobile with indistinct margins. There was no history of trauma/malignancy.

Imaging Findings

Digital Mammogram

A slightly irregular, high density mass, with micro lobulations was located in the upper outer quadrant and the reteroaereolar region of the left breast. (FIGURE 1). No associated microcalcifications, skin changes or nipple retraction were noted. The right breast was unremarkable.

Ultrasound

A slightly irregular, heterogeneously hypoechoic mass, measuring 42x18mm, with micro lobulated margins was seen in the upper outer region and the retroaereolar region of the left breast. (FIGURE 2). Moderate internal vascularity was noted. (FIGURE3). No other focal abnormality or associated gynecomastia was noted in either breast. Both axillae were unremarkable. Combined BIRADS of 4b was assigned.

A core biopsy was performed under sonographic guidance. (FIGURE 4) The histological diagnosis was that of a low-grade spindle cell lesion, favoring myofibroblastoma which was CD 34 and ER-positive (Estrogen receptor) and negative for CK (Cholecystokinin) and Desmin on Immunohistochemistry. These results were concordant with the results post excisional biopsy.

Discussion

Benign breast diseases are still considered the largest cause of breast complaints.[1] Inflammatory myofibroblastic tumours (IMTs), first reported by Brunn in 1939, are rare benign tumor-like inflammatory lesions infiltrated by myofibroblasts and inflammatory cells such as lymphocytes and plasmacytes.[1] In 2002, WHO officially designated the IMT name and defined these tumors as intermediate, occasionally metastatic and locally recurrent tumours. IMTs can develop in various tissue types at all ages, with the most common sites of localisation including lung, liver, mesentery, omentum, and peritoneum.

Myofibroblastoma is a rare benign mesenchymal tumour which usually occurs in the breast parenchyma of both females and males [2]. Most cases of myofibroblastoma occur most often in women and men aged 40–87 years. It tends to affect older men and postmenopausal women [3- 6].

Coffin has classified IMTs into 3 categories: (1) myxoid pattern, or angioid type, or nodular fasciitis type; (2) dense spindle cell type or fibrous histiocytoma pattern; (3) hypocellular fibrous pattern or desmoid fibromatosis. This second category is the most common form of IMT, and the category to which our case belonged[7-10]. While mammary myofibroblastoma is pathologically classified as a benign spindle cell tumour of the mammary stroma [10,11], nonspecific imaging features at presentation necessitate tissue sampling for pathologic diagnosis.[12,13]. This was particularly true for the patient in our case, as primary breast neoplasms were also amongst the differential diagnosis. Pathologists must carefully evaluate collected specimens as immunohistochemical and morphological variants of mammary myofibroblastoma include entities resembling malignancies [12], including epithelioid and deciduoid cell variants.

Characteristically, these lesions present as a solitary, painless, firm, and freely mobile mass which grows slowly for several months or years [13,14]. An association with gynecomastia has been reported but was absent in our case. Mammography tends to demonstrate a well-circumscribed, round to oval, dense mass with rare coarse calcifications [15,16].

Sonographically, this neoplasm presents as a well-circumscribed, round to oval mass as well, with variable echogenicity [15, 17]. Thus, nonspecific imaging features necessitate tissue sampling for pathologic diagnosis. Myofibroblastoma can be treated with local excision.

Immunohistochemistry may show tumour cells are positive for CD34(cluster of differentiation 34) and desmin in approximately 89% and 91% of the cases; respectively. Tumour has been reported to be positive for BCL-2(B-cell lymphoma-2), CD99 and Smooth Muscle Actin (SMA). Other immunohistochemical markers that may aid in the diagnosis include Pan-cytokeratin and S100; both are typically negative in the neoplastic cells. (18) Our patient was positive for CD34 and ER favoring our diagnosis and negative for cytokeratin.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Low Grade Mesenchymal Tumor positive for CD34 and ER and negative for cytokeratin, favouring Intramammary myofibroblastoma
Invasive Ductal Carcinoma
Invasive Lobular Carcinoma
Granular cell tumour
Leiomyoma
Pseudo Angiomatous Stromal Hyperplasia
Metastasis
Final Diagnosis
Low Grade Mesenchymal Tumor positive for CD34 and ER and negative for cytokeratin, favouring Intramammary myofibroblastoma
Case information
URL: https://www.eurorad.org/case/16978
ISSN: 1563-4086
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