ALK-1 protein expression and ALK gene rearrangements aid in the diagnosis of inflammatory myofibroblastic tumors of the female genital tract.
BACKGROUND
Inflammatory myofibroblastic tumor is a predominantly benign, spindle cell, mesenchymal neoplasm with myxoid areas that occurs rarely in the female genital tract and may be confused with other spindle cell lesions, particularly leiomyosarcoma.


OBJECTIVE
To investigate the utility of detecting anaplastic lymphoma kinase-1 protein expression and ALK gene rearrangements in the diagnosis of inflammatory myofibroblastic tumors in the female genital tract.


METHODS
Eight inflammatory myofibroblastic tumors arising in the female genital tract and seen in consultation (from 2004 to 2011) were reviewed. Immunohistochemistry for anaplastic lymphoma kinase-1 and fluorescence in-situ hybridization studies for ALK gene rearrangements were performed.


RESULTS
The anatomic sites included myometrium (4 cases) and endometrium, fallopian tube, cervix, and a cervical polyp (1 each), with a patient age range from 25 to 52 years. Histologic features ranged from bland spindle cells to striking cytologic atypia, embedded in a prominent myxoid background. Anaplastic lymphoma kinase-1 immunohistochemistry was positive in 7 cases. Fluorescence in-situ hybridization studies detected ALK gene rearrangements in 5 cases. Five cases had both immunopositivity and fluorescence in-situ hybridization abnormalities, 2 cases had immunopositivity only, and 1 case was negative by both methods.


CONCLUSIONS
This is the first report, to our knowledge, of ALK gene rearrangements in inflammatory myofibroblastic tumors in the female genital tract. If a myxoid background is appreciated in a spindle cell lesion of the female genital tract, especially if inflammatory cells are present, anaplastic lymphoma kinase-1 staining along with fluorescence in situ hybridization studies, for ALK gene rearrangements, may aid in distinguishing inflammatory myofibroblastic tumors from their malignant mimics.
Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905-0001, USA.
Neil E
NE
Fuehrer
Gary L
GL
Keeney
Rhett P
RP
Ketterling
Ryan A
RA
Knudson
Debra A
DA
Bell
D000328:Adult; D000077548:Anaplastic Lymphoma Kinase; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015321:Gene Rearrangement; D005831:Genital Diseases, Female / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008875:Middle Aged; D058628:Myofibroblasts / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism
D014408:Biomarkers, Tumor; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases