Inflammatory Myofibroblastic Tumor of the Uterus

Abstract

Inflammatory myofibroblastic tumor (IMT) is an indolent spindle cell proliferation that can histologically resemble various malignant mesenchymal neoplasms; however, it generally behaves as a benign or locally recurrent tumor. Most IMTs involve the lung, mesentery, omentum, or retroperitoneum. We report the clinical and pathologic features of six IMTs of the uterus, one of which was included in a previous report, and emphasize the histologic and immunohistochemical features that distinguish IMTs from uterine spindle cell neoplasms that require aggressive treatment. Recently, translocations of the anaplastic lymphoma kinase (ALK) gene and immunohistochemical expression of ALK have been reported in IMTs of various anatomic sites. We compared ALK expression in uterine IMTs with that in uterine mesenchymal neoplasms with which it may be confused. Patients with IMT were between 6 and 46 years of age. None had a history of abdominal surgery; three were multiparous. The IMTs ranged from 1 to 12 cm in maximum dimension. Three grew as polypoid masses that arose in the lower uterine segment, and two of these prolapsed through the cervical os. The three other tumors grew as bulky myometrial masses with focally irregular borders and infiltrated the endometrium, parametrium, or cervical stroma. There were three main microscopic patterns: a hypocellular pattern, a fascicular pattern, and a hyalinized pattern. A lymphoplasmacytic infiltrate was present in all of the tumors, and most had a myxoid background. Mitotic activity ranged from 0 to 2 mitotic figures per 10 high power fields (HPF) except in one tumor that focally had up to 8 mitotic figures per 10 HPF. No nuclear atypia or necrosis was present. Immunohistochemical expression of ALK was present in a cytoplasmic pattern in all IMTs tested. No ALK expression was identified in uterine leiomyoma (n = 7), leiomyosarcoma (n = 6), carcinosarcoma (n = 4), endometrial stromal sarcoma (n = 4), or normal uterine tissues. Follow-up ranging from 1.5 years to 5 years in 4 patients with uterine IMTs revealed no recurrence or metastasis. IMTs should be differentiated from aggressive uterine mesenchymal tumors because they can be treated conservatively and have a more favorable prognosis. ALK expression appears to be of diagnostic value in conjunction with other immunohistochemical stains.

Extrauterine inflammatory myofibroblastic tumor: A case report

“…Surgical resection is the treatment of choice. In 90% or greater cases of IMT, excision is curative, including the amelioration of associated constitutional symptoms within days or few weeks of the resection (Rabban et al, 2005). Most patients have no recurrence or metastasis within 5 years (Rabban et al, 2005).…”

“…It has been previously referred to as inflammatory pseudotumor, plasma cell granuloma, or pseudosarcomatous myofibroblastic proliferation (Shintaku and Fukushima, 2006; Coffin et al, 2007; Rabban et al, 2005). A triad of findings define IMT: 1) myofibroblastic proliferation lacking nuclear atypia; 2) lymphoplasmacytic infiltrate; 3) variable myxoid stromal background (Rabban et al, 2005). IMT was considered a reactive or inflammatory lesion, but cytogenetic studies have shown genetic rearrangements of the anaplastic lymphoma kinase (ALK) gene located in the chromosomal region 2p23 of this lesion confirmed its true neoplastic nature (Olgan et al, 2011; Rabban et al, 2005; Butrynski et al, 2010).…”

A Rare Cause of an Endobronchial Tumour in Children: The Role of Interventional Bronchoscopy in the Diagnosis and Treatment of Tumours while Preserving Anatomy and Lung Function

“…IMT is most frequently found in the thorax but cases have been reported from other sites – abdomen, retroperitoneum, head and neck, soft tissues, genitourinary tract and central nervous system [1]. IMT is also known in the literature as inflammatory pseudotumour, plasma cell granuloma, inflammatory myofibrohistiocytic proliferation and inflammatory fibrosarcoma [2].…”

“…IMT is a benign tumour [1]. However, recurrent and multifocal forms have been described which have the tendency to have aggressive local behaviour with invasion of adjacent structures.…”

Rare Gastric Inflammatory Myofibroblastic Tumor in an Adult Woman: A Case Report with Review of the Literature

“…At the molecular level, approximately half of IMTs contain a clonal cytogenetic aberration that activates the anaplastic lymphoma kinase (ALK-) receptor tyrosine kinase gene at 2p23. Positive immunohistochemical staining of ALK is approximately in 40–100% of IMTs, depending on the anatomic sites [6–9]. ALK expression distinguishes IMT from other differential diseases diagnostic, such as fibromatosis, nodular fasciitis, leiomyosarcoma, and gastrointestinal stromal tumor, which do not express ALK [1].…”