Transcription factor E3 (TFE3) represents a useful target for immunohistochemistry assays in routine surgical pathology practice. This protein has shown nuclear expression in a variety of normal tissues; however, this expression is usually at very low levels, while strong nuclear immunoreactivity of TFE3 has been seen almost exclusively in tumors. We present the case of a 30-year-old female on oral contraceptive pill (drospirenone/ethinylestradiol) and with complaints of dysmenorrhea and menorrhagia. She was found to have a cervical mass on pelvic ultrasound, and the biopsy showed fragments of benign squamous epithelium and polypoid endometrial tissue with stromal pseudodecidualization and abundant mixed inflammation. The pseudodecidualized stromal component showed moderate to strong nuclear staining in ~85% of stromal cells for TFE3. We discuss the intracellular role of TFE3 during inflammatory states and hypothesize that TFE3 expression can be associated with ongoing inflammation. Our case shed light upon the possibility that non-neoplastic environments with an inflammatory background could lead to increased nuclear expression of TFE3. Pathologists should be aware of the possibility of strong nuclear expression of TFE3 in non-neoplastic endometrium to avoid potential misdiagnosis.
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