Teaching casePost-traumatic inflammatory pseudotumor of the breast with atypical morphological features: A potential diagnostic pitfall. Report of a case and a critical review of the literature
Introduction
The terms “inflammatory pseudotumor” (IPT) or “inflammatory myofibroblastic tumor” (IMT) are still used interchangeably in the literature to describe controversial fibro-inflammatory lesions that include different biological entities, ranging from reactive lesions to potentially metastasizing tumors [6], [7], [9], [13], [24], [25], [31]. However, despite its morphological and immunohistochemical overlapping with IPT, over the last years, IMT has emerged as a distinct tumor entity that characteristically occurs in the lung, upper aerodigestive airways, abdomen, pelvis, and retroperitoneum of children and adolescents [6], [9], [13], [31]. Notably, this tumor harbors rearrangements of the ALK gene on the short arm of chromosome 2 at 2p23 in approximately 40–50% of cases [8]. IPT encompasses a wide spectrum of both idiopathic and secondary (post-infectious/reparative) fibro-myofibroblastic lesions for which a plethora of terms has been used, including plasma cell granuloma, pseudomalignant spindle cell proliferation, postinflammatory tumor, pseudosarcomatous fibromyxoid tumor, nodular fasciitis, inflammatory pseudotumor, post-operative spindle cell nodule, or pseudosarcomatous myofibroblastic proliferation [6], [9], [13], [28], [31]. Although some authors claim that a distinction between IMT and IPT is possible in most cases [13], others believe that their separation based on morphological and immunohistochemical features is challenging [17], suggesting that they are variations of a single disease, especially in some organs such as bladder [12], [32]. Apart from the typical anatomic sites, lesions labeled as “IMT and/or IPT” have been reported to occur virtually in any site of body [13], [33], including the breast [1], [3], [5], [6], [14], [15], [18], [19], [20], [25], [26], [29], [34], [35], [36].
We herein report the first case of an IPT of the breast parenchyma, developing after a recent mechanical trauma.
Section snippets
Clinical history
A 22-year-old male patient presented with a mass in his left breast. Clinical examination showed a painless, palpable lesion, with relatively circumscribed margins, only partially mobile, non-adhesive to the deep layers. The patient had a mechanical chest trauma due to a direct blow on the same site of the lesion four months earlier, caused by the fall of an heavy object during its transport. There was no history of previous breast surgery or use of exogenous hormones. Ultrasonography
Materials and methods
The surgical specimen was submitted for histological examination in neutral-buffered 10% formalin, dehydrated using standard techniques, embedded in paraffin, cut to 5 μm, and stained with hematoxylin and eosin. Immunohistochemical studies were performed with the labeled streptavidin–biotin peroxidase detection system using the Ventana automated immunostainer (Ventana Medical Systems, Tucson, AZ). The following antibodies were tested: vimentin, α-smooth muscle actin, desmin, cytokeratins (CK
Pathological findings
The surgical specimen comprised breast parenchyma measuring 11 cm in its greatest diameter. The cut section revealed a 7-cm, ill-defined solid-cystic mass, whitish in color, with extensive areas of hemorrhage. Histologically, the mass was partially surrounded by a thick fibrous pseudocapsule and involved the breast parenchyma with focal extension into subcutis. At low magnification, the lesion showed high cellularity and a prominent fascicular growth pattern (Fig. 2A). Only focally was a
Discussion
The etiology of IMT/IPT of any site is still a matter of debate. The controversial question about its pathogenesis is whether it is a reactive lesion or a “true” neoplasm. The hypothesis that IMT/IPT is the result of an abnormal reactive/reparative process seems to be supported by the evidence that a bacterial or fungal cause or a previous history of infarcts or prior radiation therapy can be demonstrated in some cases [2], [13], [21], [22], [27], [33]. On the other hand, the apparently
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