Fine Needle Aspiration Cytology of Pseudosarcomatous Reactive Proliferative Lesions of Soft Tissue

Objective:Nodular fasciitis(NF),proliferative fasciitis(PF)and proliferative myositis(PM)are the most common pseudosarcomatous reactive proliferative lesions of soft tissue.These lesions often resolve spontaneously.The aims of this study were to summarize the diagnostic features of fine needle aspiration cytology(FNAC)of pseudosarcomatous reactive proliferative lesions of soft tissue and to establish the criteria in differentiating these lesions from true sarcoma,thus allowing conservative management.Methods:FNAC of 17 cases(13 NF,2 PF,2 PM),from 1994 to 2001,were reviewed in correlation with the clinical course or results of biopsy.Results:The FNAC features of pseudosarcomatous reactive proliferative soft tissue lesions were characterized by a pleomorphic pattern of the proliferative cells and the presence of ganglion-cell-like cells.The proliferative cells varied widely from spindle shaped with long cytoplasmic processes to more plump cells with round to oval nuclei.In spite of the large nuclei and prominent nucleoli in ganglion-cell-like cells,the nuclei were cytologically benign with thin and smooth nuclear membranes and fine chromatin.Clinically,all lesions appeared as small,superficially located,rapidly growing nodules with short duration of symptoms.Ten cases of NF,one case of PF and two cases of PM showed spontaneous resolution in 1-12 weeks(mean 4.7 weeks)following diagnosis by FNAC.All patients were clinically well and devoid of any symptoms or signs of recurrence or metastasis in a follow-up period of 1-64 months after FNAC or biopsies.Conclusions:It is possible to differentiate pseudosarcomatous reactive proliferative soft tissue lesions from true sarcoma based on cytological criteria in FNAC together with clinical correlation.All such lesions diagnosed by FNAC should be managed non-surgically first,with follow-up.If regression does not occur within 4 to 8 weeks,surgery should then be performed.