Inflammatory pseudotumor of the breast. Report of a case and review of the literature

Inflammatory pseudotumor (IPT) truly represents an enigmatic entity. A tumor-like lesion known with many synonyms according to the various patronymic authors who named it on the basis of the different observed morphological appearances. Among these names plasma cell granuloma, plasma cell/histiocytoma complex, xanthomatous pseudotumor, xanthoma, fibrous xanthoma, histiocytoma, xanthogranuloma, inflammatory myofibroblastic tumor, inflammatory myofibrohistiocytic proliferation are just the most renown. The enigma consists in the fact that it can easily be misunderstood as a sarcoma with a marked inflammatory component just as reciprocally an inflammatory sarcoma can be misinterpreted as an IPT. As it was not enough some authors believe that some so-called IPT actually represent or may evolve into a true neoplastic process. For this reason a big debate has been raised concerning the biologic behaviour of this entity and a sense of scepticism often surrounds pathological diagnoses termed under this rubric. The predominant pattern is that of a plasma cell infiltration with a definitely histiocytic component and mostly bland spindle shaped cells which occasionally can look somewhat atypical, and can form fascicles in some areas. Anyway putting apart diagnostic misinterpretations, IPT pathogenetically is intended as the result of an inflammatory process mediated locally by an inappropriate production of monokines. It has been described in many different anatomic visceral and somatic sites, from the classical ones such as soft tissues and retroperitoneum to the most unusual such as nervous system and its covering to the most recently observed such as skin or lymph nodes or salivary glands. Breast is definitely an exoteric site of location of such kind of lesion. Only one case has previously been described. This case regards a lady aged 38 years which was locally treated by surgical excision: this case aside the standard microscopic examination was also studied immunohistochemically including proliferation markers (Ki-67/MIB-1) and on flow cytometry which are helpful means to confidently diagnose such entity. The differential diagnoses and diagnostic difficulties concerning the correct interpretation of this lesion are dealt with.