title: Extraskeletal myxoid chondrosarcoma: multimodal diagnosis and identification of a new cytogenetic subgroup characterized by t(9;17)(q22;q11).
abstract: Extraskeletal myxoid chondrosarcoma is a rare malignant soft tissue tumour that can be difficult to diagnose correctly, especially preoperatively. We describe four cases of extraskeletal myxoid chondrosarcoma of the extremities diagnosed by a multimodal approach. The cytological examination of fine-needle aspirates showed small and round, mildly pleomorphic cells lying in sheets and cords, but also dispersed within a myxoid and metachromatic intercellular substance. Histological, electron microscopic and immunocytochemical examination also yielded findings compatible with the diagnosis of extraskeletal myxoid chondrosarcoma. Cytogenetic analysis demonstrated a t(9;22)(q22;q12) in two tumours and a t(9;17)(q22;q11) in the third and fourth. The translocation t(9;22)(q22;q12) has been described repeatedly in extraskeletal myxoid chondrosarcoma but never in other tumours; hence, the detection of this pathognomonic chromosome abnormality in short-term cultured cells from fine-needle aspirates verified the diagnosis in two of the cases. The t(9;17)(q22;q11) found in the last two cases probably represents a new cytogenetic subgroup of extraskeletal myxoid chondrosarcoma as it, too, is unknown in other contexts. The multimodal approach taken in these four cases enabled a definite diagnosis of a rare malignant tumour whose cytological and histological features alone are usually not sufficiently distinct to rule out other differential diagnostic possibilities.
authors.affiliation: Department of Pathology, The Norwegian Radium Hospital and Institute for Cancer Research, University of Oslo, Oslo, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Bjerkehagen
authors.forename: C
authors.initials: C
authors.lastname: Dietrich
authors.forename: W
authors.initials: W
authors.lastname: Reed
authors.forename: F
authors.initials: F
authors.lastname: Micci
authors.forename: G
authors.initials: G
authors.lastname: Saeter
authors.forename: A
authors.initials: A
authors.lastname: Berner
authors.forename: J M
authors.initials: JM
authors.lastname: Nesland
authors.forename: S
authors.initials: S
authors.lastname: Heim
mesh_terms: D000368:Aged; D002813:Chondrosarcoma / Q000145:classification / Q000175:diagnosis* / Q000235:genetics* / Q000648:ultrastructure; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D003937:Diagnosis, Differential; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D007621:Karyotyping; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000145:classification / Q000175:diagnosis / Q000235:genetics* / Q000648:ultrastructure; D014178:Translocation, Genetic