title: Omental mesenteric myxoid hamartoma, a subtype of inflammatory myofibroblastic tumor? Considerations based on the histopathological evaluation of four cases.
abstract: Omental mesenteric myxoid hamartoma (OMH) is a distinctive myxoid lesion of infancy, characterized by a benign clinical behavior. In the current World Health Organization (WHO) classification of soft tissue tumors, it is considered as part of the morphologic spectrum of inflammatory myofibroblastic tumors (IMT), but this relationship with IMT is still subject to debate. Four lesions with histologic features of OMH occurring in newborns and toddlers are described and compared with classic, ALK-positive IMT. All OMH showed a peculiar dot-like immunostaining for ALK, which, in one of the cases, was cytogenetically found to be associated with an inversion of the ALK gene. While OMHs were positive for smooth muscle actin (SMA), desmin, WT1, podoplanin, and cytokeratins (CAM5.2 and AE1-3), IMT were consistently positive only for SMA (10 cases). ALK-1 displayed cytoplasmic staining in IMT and characteristic paranuclear dot-like staining in OMH.
authors.affiliation: Department of Medicine (DIMED), Surgical Pathology & Cytopathology Unit, University-Hospital of Padua, Via A. Gabelli 61, 35121, Padua, Italy.
authors.forename: K
authors.initials: K
authors.lastname: Ludwig
authors.affiliation: Department of Medicine (DIMED), Surgical Pathology & Cytopathology Unit, University-Hospital of Padua, Via A. Gabelli 61, 35121, Padua, Italy. ral@unipd.it.
authors.forename: R
authors.initials: R
authors.lastname: Alaggio
authors.affiliation: Department of Woman and Children's Health, Pediatric Surgery Unit, University-Hospital of Padua, Via Giustiniani 3, 35121, Padua, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Dall'Igna
authors.affiliation: Pathology Department, "San Bortolo" Hospital, Vicenza, Viale Rodolfi 37, 36100, Vicenza, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Lazzari
authors.affiliation: Pathology Department, "San Bortolo" Hospital, Vicenza, Viale Rodolfi 37, 36100, Vicenza, Italy.
authors.forename: E S G
authors.initials: ES
authors.lastname: d'Amore
authors.affiliation: Department of Pathology, Northwestern University, 303 East Chicago Avenue, Chicago, IL, 60611, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Chou
keywords: Inflammatory fibrosarcoma; Inflammatory myofibroblastic tumor; Myofibroblast; Omental myxoid hamartomas of the peritoneum; Peritoneal tumors; Submesothelial tissue; Subserosal cells