title: Renal leiomyoma: a contemporary multi-institution study of an infrequent and frequently misclassified neoplasm.
abstract: Renal leiomyoma is an exceptionally rare benign mesenchymal tumor of the kidney predominantly arising in proximity of the renal capsule or pelvis. Its rarity and nonspecific clinical and imaging features may lead to radical or partial nephrectomy on the basis of preoperative suspicion of renal cell carcinoma. The diagnosis of renal leiomyoma is challenging because of the histologic overlap with lipid-poor angiomyolipoma (AML). We conducted a multi-institution study to characterize renal leiomyoma in greater detail. We collected and reviewed 24 cases diagnosed initially as renal leiomyoma in 10 institutions from North America, Canada, and Europe. Immunohistochemical expression of desmin, HMB-45, estrogen receptor (ER), progesterone receptor (PR), and cathepsin K was evaluated. Upon central review, 9 tumors were classified as renal leiomyoma, whereas the remaining were reclassified as AML (n=13), myolipoma (n=1), and medullary fibroma (n=1). All renal leiomyomas were solitary and occurred in female patients (mean age 63 y; range, 44 to 74 y). Tumor size ranged from 0.6 to 7.0 cm (mean 2.9 cm); 7 originated from the renal capsule or the subcapsular area and 1 from a large vessel in the renal sinus. All leiomyomas were diffusely positive for desmin and negative for HMB-45 and cathepsin K; 6/9 (67%) showed diffuse ER and PR expression, and 1 case showed focal ER positivity only. Renal leiomyoma should be included in the histologic differential diagnosis of solid renal masses, particularly in perimenopausal women. The main differential diagnosis is with lipid-poor AML, and cathepsin K plays a key role in distinguishing these 2 lesions.
authors.affiliation: *Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH ¶Keck School of Medicine, University of Southern California, Los Angeles #Department of Anatomic Pathology, El Camino Hospital, Mountain View, CA **Department of Pathology, Rush University Medical Center, Chicago, IL †Department of Pathology and Laboratory Medicine, University of Calgary and Calgary Laboratory Services, Calgary, AB, Canada ‡Department of Pathology, Medical Faculty and Charles University, Pilsen, Czech Republic §Department of Pathology, University of Ancona, Ancona, Italy ∥Department of Pathology and Oncology, University of Florence, Firenze, Italy.
authors.forename: Pallavi A
authors.initials: PA
authors.lastname: Patil
authors.forename: Jesse K
authors.initials: JK
authors.lastname: McKenney
authors.forename: Kiril
authors.initials: K
authors.lastname: Trpkov
authors.forename: Ondrej
authors.initials: O
authors.lastname: Hes
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Montironi
authors.forename: Marina
authors.initials: M
authors.lastname: Scarpelli
authors.forename: Gabriella
authors.initials: G
authors.lastname: Nesi
authors.forename: Manju
authors.initials: M
authors.lastname: Aron
authors.forename: Ankur R
authors.initials: AR
authors.lastname: Sangoi
authors.forename: Paolo
authors.initials: P
authors.lastname: Gattuso
authors.forename: Cristina
authors.initials: C
authors.lastname: Magi-Galluzzi
mesh_terms: D000328:Adult; D000368:Aged; D018207:Angiomyolipoma / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis; D003937:Diagnosis, Differential; D005060:Europe; D005260:Female; D005350:Fibroma / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D007889:Leiomyoma / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D008067:Lipoma / Q000737:chemistry / Q000145:classification / Q000473:pathology*; D008875:Middle Aged; D009656:North America; D011237:Predictive Value of Tests
chemical_list: D014408:Biomarkers, Tumor