Myositis ossificans – Another condition with USP6 rearrangement, providing evidence of a relationship with nodular fasciitis and aneurysmal bone cyst

• Published in: Annals of diagnostic pathology Vol. 34; pp. 56 - 59
• Main Authors: Bekers, Elise M., Eijkelenboom, Astrid, Grünberg, Katrien, Roverts, Rona C., de Rooy, Jacky W.J., van der Geest, Ingrid C.M., van Gorp, Joost M., Creytens, David, Flucke, Uta
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2018
• Subjects: Adolescent; Adult; Bone Cysts, Aneurysmal - diagnostic imaging; Bone Cysts, Aneurysmal - genetics; Bone Cysts, Aneurysmal - pathology; Child; Fasciitis - diagnostic imaging; Fasciitis - genetics; Fasciitis - pathology; Female; Gene Rearrangement; Humans; In Situ Hybridization, Fluorescence; Magnetic Resonance Imaging; Male; Myositis ossificans; Myositis Ossificans - diagnostic imaging; Myositis Ossificans - genetics; Myositis Ossificans - pathology; Proto-Oncogene Proteins - genetics; Soft Tissue Neoplasms - diagnostic imaging; Soft Tissue Neoplasms - genetics; Soft Tissue Neoplasms - pathology; Soft tissue tumors; Ubiquitin Thiolesterase - genetics; USP6 rearrangement; Young Adult; USP6 rearrangement; Soft tissue tumors; Myositis ossificans
• ISSN: 1092-9134; 1532-8198
• DOI: 10.1016/j.anndiagpath.2018.01.006

Myositis ossificans is defined as a self-limiting pseudotumor composed of reactive hypercellular fibrous tissue and bone. USP6 rearrangements have been identified as a consistent genetic driving event in aneurysmal bone cyst and nodular fasciitis. It is therefore an integral part of the diagnostic workup when dealing with (myo)fibroblastic lesions of soft tissue and bone. Two cases of myositis ossificans with USP6 rearrangement were published so far. We determine herein the incidence of USP6 rearrangement in myositis ossificans using USP6 fluorescence in situ hybridization analysis (FISH). Of the 11 cases included, seven patients were female and four were male. Age ranged from 6 to 56 years (mean 27 years). Lesions were located in the thigh (n = 5), knee (n = 1), lower leg (n = 1), lower arm (n = 1), perineum (n = 1), gluteal (n = 1) and thoracic wall (n = 1). All assessable cases except one (8/9) showed rearrangement of USP6 providing evidence that myositis ossificans is genetically related to nodular fasciitis and aneurysmal bone cyst. •We have identified USP6 rearrangements in a series of myositis ossificans cases.•We therefore argue that this entity belongs to the group of clonal transient neoplasms also including nodular fasciitis and aneurysmal bone cyst.