Myofibroblastoma of the axilla

Extramammary myofibroblastoma in the head and neck region

BACKGROUND

Mammary myofibroblastoma is a benign mesenchymal tumor of the breast. Extramammary location is very rare and usually occurs along the embryonic milk-line.

METHODS AND RESULTS

In this article, we present a case of a woman with an infra-auricular swelling. A diagnosis could not be made on CT scans, so the mass was surgically removed. Histological examination showed spindle cells in clusters, with CD34, desmin, and actin expression. The diagnosis of extramammary myofibroblastoma was made.

CONCLUSION

We describe this case because of the unusual location of this rare tumor. Furthermore, we want to highlight the possible relationship between (extra)mammary myofibroblastoma and spindle cell lipoma (SCL). SCL has a predilection site in the posterior neck. Both tumors show the same clinical behavior, a close histological resemblance, and their cells are both immunoreactive for CD34 and CD10. The loss of RB/13q14 and FKHR/13q14 loci, which is typically found in SCL cells, was also shown in this case.

Mammary-type myofibroblastoma of soft tissue: a tumor closely related to spindle cell lipoma

Mammary myofibroblastoma is a benign breast tumor, with a reported predilection for older men. It is composed of fascicles of spindle cells having features of myofibroblasts, with intervening hyalinized collagenous stroma and a variably prominent component of adipose tissue. The spindle cells characteristically express both CD34 and desmin. Herein, we report the clinicopathologic features of nine tumors that were morphologically and immunohistochemically identical to myofibroblastoma of breast; however, they arose in subcutaneous soft tissue at extramammary sites. The study group comprised seven men and two women with an age range of 35-67 years (median 53 years). Lesions presented as either a slowly growing painless mass or were incidental findings at the time of surgery. The site distribution was as follows: inguinal/groin area (five cases) and one case each in posterior vaginal wall, buttock, anterior abdominal wall, and mid-back. Tumor size ranged from 2 to 13 cm (median 6 cm), and all lesions were well circumscribed. Eight tumors had a component of adipose tissue (ranging from 10% to 60%), within which some variation in adipocyte size was often seen. One case showed epithelioid cytomorphology and three cases showed rare atypical or multinucleated cells. Focal myxoid stromal change was seen in four cases. Tumor cells were positive for desmin (9 of 9 cases), CD34 (8 of 9 cases), and occasionally positive for smooth muscle actin (3 of 9 cases). Lesions were marginally excised with no recurrences to date, although follow-up is very limited. Lesions with morphologic and immunophenotypic features similar to myofibroblastoma of breast can arise at extramammary sites, with an apparent predilection for the inguinal area of older men. Both mammary and extramammary lesions show morphologic overlap with spindle cell lipoma and are likely closely related.

Myofibroblastoma of the breast with hemangiopericytoma-like pattern and pleomorphic lipoma-like areas. Report of a case with diagnostic and histogenetic considerations

Myofibroblastoma (MFB) of the breast is an uncommon benign spindle cell tumor which may exhibit a wide spectrum of histological features. We report an unusual case of MFB of the male breast, showing cellular areas with a hemangiopericytoma-like pattern similar to that observed in solitary fibrous tumor (SFT) and extensive fibromyxoid areas containing numerous atypical stromal cells. The association of these atypical cells with mature adipocytes and microcystic and/or myxoid degenerative changes resembled pleomorphic lipoma-like and myxoid liposarcoma-like features, respectively. To our knowledge, these peculiar morphological findings have not been previously reported in MFB of the breast. They should be recognized to avoid confusion with other mesenchymal tumors, especially with hemangiopericytoma, pleomorphic lipoma (PL), spindle-cell lipoma (SCL) and myxoid liposarcoma. A case of MFB of the breast showing morphological features also commonly seen in SFT and PL/SCL is further morphological evidence in support of the speculation that the mesenchymal tumors of the breast, also known under the terms benign spindle cell tumors, fibromas, SFTs, SCLs and MFBs, are histogenetically related lesions.