title: ALK expression in pseudosarcomatous myofibroblastic proliferations of the genitourinary tract.
abstract: OBJECTIVE
  Pseudosarcomatous myofibroblastic proliferation of the genitourinary tract is rare and may develop after trauma or spontaneously. The aim of this study was to characterize further the clinicopathological features of these lesions and to examine their relationship to inflammatory myofibroblastic tumour (IMT).
  
  
  RESULTS
  Twenty-seven cases of pseudosarcomatous myofibroblastic proliferation were analysed. There were seven males and 20 females; median age was 37 years (range 16-88). Most lesions were from the bladder (n = 21), while others were in the urethra, vulva, vagina, rectum and retrovesical space. Median tumour size was 30 mm (range 6-120 mm). Seven cases (25%) had a history of prior trauma or surgery. Three cases recurred locally but not destructively. The tumours had fasciitis-like features including bland spindle cells with evenly distributed chromatin, admixed inflammatory cells (mainly lymphocytes) and often a myxoid stroma. Immunohistochemistry showed positivity for smooth muscle actin in 14/20 cases, keratin in 8/19, desmin in 7/20 and anaplastic lymphoma kinase (ALK) in 10/21 cases. Fluorescent in situ hybridization was performed in six ALK+ cases; all were negative for ALK gene rearrangement.
  
  
  CONCLUSIONS
  Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract may show ALK immunopositivity but do not show consistent ALK rearrangement. Given subtle morphological differences and more consistently benign behaviour, their relationship to inflammatory myofibroblastic tumour at other sites remains uncertain.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Hirsch
authors.forename: P
authors.initials: P
authors.lastname: Dal Cin
authors.forename: C D M
authors.initials: CD
authors.lastname: Fletcher
mesh_terms: D000199:Actins / Q000032:analysis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077548:Anaplastic Lymphoma Kinase; D003893:Desmin / Q000032:analysis; D005260:Female; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007633:Keratins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000737:chemistry; D047708:Myofibroma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases; D012509:Sarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D014523:Urethral Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
chemical_list: D000199:Actins; D003893:Desmin; D007633:Keratins; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases