title: Anaplastic lymphoma kinase (ALK) expression in the inflammatory myofibroblastic tumor: a comparative immunohistochemical study.
abstract: Inflammatory myofibroblastic tumor (IMT) is an uncommon mesenchymal neoplasm with a variable histologic appearance that may mimic other spindle cell processes, particularly nodular fasciitis, desmoid tumor, and in intra-abdominal locations, gastrointestinal stromal tumor. Recently, gene fusions involving ALK at chromosome 2p23 have been described in IMTs. The resultant ALK protein overexpression in the myofibroblastic component of these tumors is detectable by immunohistochemistry. We examined 73 IMTs, 20 cases of nodular fasciitis, 15 desmoid fibromatoses, and 15 gastrointestinal stromal tumors by immunohistochemistry using ALK-11, a rabbit polyclonal antibody that recognizes the C-terminus of the protein. ALK positivity was detected in 44 of 73 (60%) IMTs. All cases of nodular fasciitis, desmoid fibromatosis, and gastrointestinal stromal tumors were ALK negative (p < 0.001). These findings demonstrate that ALK positivity is common in IMTs, and immunohistochemistry using anti-ALK antibodies can be helpful in the differential diagnosis of these neoplasms. In addition, anti-ALK staining seems to correlate with those IMTs that have the typical tri-patterned histologic appearance and clinical presentation, providing additional support to the premise that IMT is a distinctive clinicopathologic entity within the broad category of inflammatory pseudotumors.
authors.affiliation: Lauren V. Ackerman Division of Surgical Pathology, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Cook
authors.forename: L P
authors.initials: LP
authors.lastname: Dehner
authors.forename: M H
authors.initials: MH
authors.lastname: Collins
authors.forename: Z
authors.initials: Z
authors.lastname: Ma
authors.forename: S W
authors.initials: SW
authors.lastname: Morris
authors.forename: C M
authors.initials: CM
authors.lastname: Coffin
authors.forename: D A
authors.initials: DA
authors.lastname: Hill
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000077548:Anaplastic Lymphoma Kinase; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005208:Fasciitis / Q000378:metabolism / Q000473:pathology; D005260:Female; D018222:Desmoid Tumors / Q000378:metabolism / Q000473:pathology; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000473:pathology; D006104:Granuloma, Plasma Cell / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000096:biosynthesis*; D020794:Receptor Protein-Tyrosine Kinases; D012983:Soft Tissue Neoplasms / Q000201:enzymology* / Q000473:pathology; D017154:Stromal Cells / Q000737:chemistry / Q000473:pathology
chemical_list: C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases