Inflammatory myofibroblastic tumor of the uterus – case report

Czech version

Authors: Zuzana Štiková ¹; Nikola Ptáková ¹; Markéta Horáková ^1,3; Jan Kosťun ²; Ondrej Ondič ^1,3
Authors‘ workplace: Bioptická laboratoř s. r. o., Plzeň ¹; Gynekologicko-porodnická klinika, LF UK a FN Plzeň ²; Šiklův ústav patologie, LF UK a FN Plzeň ³
Published in: Čes.-slov. Patol., 55, 2019, No. 4, p. 239-243
Category: Original Articles

Overview

Inflammatory myofibroblastic tumor (IMT) of the uterus is rare but probably underdiagnosed tumor. It is usually benign but small fraction of cases may locally recur or rarely metastasize. Herein, we present a case report of 66-year-old patient with uterine IMT originally diagnosed as leiomyosarcoma of the uterus. The patient died within few months due to local tumor progression with skeletal metastases. Macroscopically, this was a voluminous locally aggressive yellowish-grey tumor of soft consistency limited to myometrium. Microscopically, the tumor was characterized by polymorphic spindle cell proliferation with marked nuclear atypia and numerous mitoses. Small geographic necroses was noticed. Typical histologic features of IMT were represented by lymphocytic infiltrate which was only very small and focal. Myxoid stroma was absent. Immunohistochemically, there was strong and diffuse cytoplasmic positivity of ALK (anaplastic lymphoma kinase). The presence of PPP1CB-ALK fusion transcript was confirmed by molecular-genetic methods. Proper diagnosis of uterine IMT is of importance as there is an option of targeted ALK inhibitor therapy in cases of aggressive tumor behaviour. Currently it is thought that histomorphology of uterine IMT may overlap with that of leiomyosarcoma and STUMP (smooth muscle tumor of uncertain malignant potential). The presence of ALK rearrangement is probably the only reliable diagnostic marker. Thus, ALK immunohistochemistry followed by molecular-genetic testing seems to represent suitable screening tool for the detection of uterine IMT.

Keywords:

Leiomyosarcoma – inflammatory myofibroblastic tumor – IMT – STUMP – Uterus – ALK-rearranged mesenchymal tumors – PPP1CB-ALK fusion – tyrosin kinase inhibitors

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