Mesenchymal lesions of the breast

Abstract

Mesenchymal lesions of the breast are a heterogeneous range of entities with diverse clinical, histological, and molecular features, as well as biological behaviour. Their morphologic overlap with non‐mesenchymal lesions (such as metaplastic carcinoma and phyllodes tumour) and relative rarity also pose significant diagnostic challenges. In this review, we summarize the salient features of selected mesenchymal lesions of the breast, emphasizing those that are the most common and problematic. Vascular, fibroblastic/myofibroblastic, adipocytic, and smooth muscle lesions are each covered with regard to their clinicopathological features and differential diagnosis, while recent advances and the role of immunohistochemistry and molecular tests are also highlighted.

Angiolipoma an Uncommon Breast Mass in Men

“…17 First, traditional lipomas are comprised mainly of mature adipocytes and lack cytologic atypia which present on clinical exam as palpable soft masses. 5,6 Similarly, fat necrosis can present as a palpable fixed mass on physical exam but pathologically demonstrates adipocytes with foamy macrophages. A defining characteristic of fat necrosis is that it often correlates with an area of trauma, unlike angiolipomas.…”

“…5,18 Hemangiomas are another benign lesion with vascular components which may be hyperechoic on ultrasound; however, their appearance is variable. 5,19 Cellular angiolipoma is a rare variant of angiolipoma which has similar sonographic findings of conventional angiolipoma, but pathologically it shows densely cellular areas in 90% or more of the tumor. 20 Lastly, angiosarcoma is a malignant lesion that shares some similarities with benign angiolipomas.…”

“…Hyperechoic breast masses have a differential diagnosis which includes lipomas, fat necrosis, hemangiomas, pseudoangiomatous stromal fibrosis, angiolipomas, angiosarcomas and rarely invasive lobular carcinoma, metastasis or lymphoma 17 . First, traditional lipomas are comprised mainly of mature adipocytes and lack cytologic atypia which present on clinical exam as palpable soft masses 5,6 . Similarly, fat necrosis can present as a palpable fixed mass on physical exam but pathologically demonstrates adipocytes with foamy macrophages.…”

“…Mammographically, they present as masses with varying shapes and densities or are mammographically occult 4 . On targeted ultrasound, they often present as a hyperechoic mass 5,6 . We present three cases of breast angiolipomas in males with corresponding clinical, mammographic, sonographic, and pathologic findings.…”

Annual Review Issue: Breast Pathology

“…These factors, together with their relative rarity, pose significant diagnostic challenges. In this ARI, Professor Christopher Fletcher and Dr William Anderson 11 summarise the salient features of selected mesenchymal lesions of the breast that are common and problematic with discussion of their clinicopathological features and differential diagnosis, including recent advances and the roles of immunohistochemistry (IHC) and molecular tests.…”