801 Do Urinary Bladder Smooth Muscle Neoplasms Show Morphologic and Immunophenotypic Features of Their Uterine Fumarate Hydratase-Deficient Counterparts?
Recommended Citation
Gao H, Ren D, Giannico G, Khani F, Galea L, Al-Obaidy K, Falzarano S, Wobker S, Barry-Holson K, Chan E, McHenry A, Sangoi A. 801 Do Urinary Bladder Smooth Muscle Neoplasms Show Morphologic and Immunophenotypic Features of Their Uterine Fumarate Hydratase-Deficient Counterparts?. Lab Invest 2025; 105(3).
Document Type
Conference Proceeding
Publication Date
3-24-2025
Publication Title
Lab Invest
Keywords
fumarate hydratase, adult, aged, anatomical location, bladder leiomyoma, bladder muscle, bladder tumor, cherry, clinical article, conference abstract, diagnosis, edema, eosinophilia, etiology, female, hereditary leiomyomatosis and renal cell cancer, histology, human, human tissue, immunohistochemistry, immunoreactivity, leiomyoma, male, smooth muscle cell, smooth muscle tumor, transurethral resection of the bladder, uterus
Abstract
Disclosures: Haijuan Gao: None; Dong Ren: None; Giovanna Giannico: None; Francesca Khani: None; Laurence Galea: None; Khaleel Al-Obaidy: None; Sara Falzarano: None; Sara Wobker: None; Keegan Barry-Holson: None; Emily Chan: None; Austin McHenry: None; Ankur Sangoi: None Background: Leiomyomas of the urinary bladder constitute <1% of all bladder tumors. While the morphologic and immunophenotypic features of smooth muscle neoplasms of the uterus and skin have been well-described in relationship to Fumarate Hydratase (FH) deficiency (FHD) and hereditary leiomyomatosis and renal cell cancer (HLRCC), a potential association of urinary bladder smooth muscle tumors with FHD/HLRCC has not been previously investigated. Design: Given an index urinary bladder transurethral resection (TURBT) leiomyoma which showed some of the purported morphologic features seen in uterine HLRCC-associated leiomyomas, herein we performed a multi-institutional search for bladder leiomyomas to further evaluate any potential HLRCC association. Slides from all cases were re-reviewed for the presence of the following well-described HLRCC-associated cytomorphologic features: macronucleoli (“cherry red”) surrounded by halo, isolated nuclear pleomorphism (“symplastic” nuclei), cytoplasmic eosinophilic globules, staghorn vasculature, alveolar-pattern edema, and chain-like distribution of smooth muscle fibers. Tumors with available material underwent whole-slide staining for FH and 2SC immunohistochemistry (IHC). Results: A total of 32 leiomyomas from were collected from 7 institutions, each from a unique patient (20 males, 12 females) aged 30-85 years (mean age: 54.6 years). Figure 1 highlights key clinicopathologic findings. Among the 32 study cases, cytoplasmic eosinophilic globules were seen most frequently (25%), followed by “cherry-red” macronucleoli with halos (19%), staghorn vasculature (13%), “symplastic” nuclei (9%), and alveolar-pattern edema (6%); no cases exhibited chain-like muscle fibers. Of the stained tumors, all (100%) showed retained FH expression and negative 2SC immunoreactivity (Figure 2). [Formula presented] [Formula presented] Conclusions: Although a subset of bladder leiomyomas show overlapping morphologic features with uterine FHD/HLRCC-associated leiomyomas, they do not appear to harbor FHD or an association with HLRCC. In the absence of a gynecologic origin for a bladder leiomyoma, despite a close anatomic location and some shared histology, it may not be necessary to pursue IHC for FHD status/HLRCC screening. Instead a focus on lineage confirmation and an evaluation for malignancy should be prioritized.
Volume
105
Issue
3
