[Clinicopathologic study of sinonasal inflammatory myofibroblastic tumor].
OBJECTIVE
To study the clinicopathologic features, immunophenotype and ultrastructural features of sinonasal inflammatory myofibroblastic tumors (IMT).


METHODS
The clinical and histologic features of 5 cases of sinonasal IMT were reviewed. Immunohistochemical study for vimentin, MSA, SMA, calponin, h-caldesmon, desmin, ALK, fibronectin, CK, S-100 and Ki-67 was carried out. Ultrastructural examination was also performed in two of the cases.


RESULTS
The patients age ranged from 28 to 62 years (mean = 43 years). The male-to-female ratio was 2:3. The clinical presentation included nasal obstruction, nasal discharge, nasal bleeding, facial pain, facial swelling, toothache and tear overflow. All of the 5 patients suffered from disease relapses; and 4 of them had recurrences for more than 5 times. One patient had lymph node metastasis and 3 patients died of the disease. Histologically, the tumor cells were arranged in interlacing fascicles and sometimes haphazard in fashion. They were spindly in shape, cytoplasm eosinophilic with mild nuclear atypia and a low mitotic activity. The intervening stroma was myxoid in appearance accompanied by lymphocyte and plasma cell infiltration, abundant blood vessels and focal collagenized areas. In 3 of the recurrent cases, the tumor cells displayed increased nuclear atypia and mitotic activity (average about 5 to 6 per 10 high-power fields), accompanied by patchy necrosis, less inflammatory cell infiltration and focal sarcomatous changes. Immunohistochemical study showed that the tumor cells were diffusely positive for vimentin. SMA, MSA, calponin and fibronectin were variably expressed. Desmin was weakly positive in 1 case. The staining for h-caldesmon, ALK, S-100 and CK was negative. The Ki-67 proliferation index increased with tumor recurrences. Electron microscopy revealed abundant rough endoplasmic reticulum and dense body formation in the cytoplasm. There were an increased amount of collagen fibers in the stroma.


CONCLUSIONS
IMT rarely occurs in nasal cavity and paranasal sinuses. The tumor is prone to local invasion and recurrences, with subsequent progression to frank malignancy and distant metastasis, resulting in high mortality and poor prognosis. Complete surgical resection remains the main modality of treatment.
He
Chun-yan
CY
Department of Pathology, Beijing Tong Ren Hospital, Capital Medical University, Beijing 100730, China.
Jin
Yu-lan
YL
Yang
Dong-mei
DM
Liu
Hong-gang
HG
D000199:Actins / Q000378:metabolism; D000328:Adult; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008207:Lymphatic Metastasis; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009379:Neoplasms, Muscle Tissue / Q000378:metabolism / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D017253:Neurofibromatoses / Q000473:pathology; D010255:Paranasal Sinus Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D014746:Vimentin / Q000378:metabolism; D000096985:Calponins
D000199:Actins; D002135:Calcium-Binding Proteins; D019394:Ki-67 Antigen; D008840:Microfilament Proteins; D014746:Vimentin; D000096985:Calponins; C541116:ACTA2 protein, human