nodular fasciitis ( nf ) , proliferative fasciitis ( pf ) and proliferative myositis ( pm ) are reactive lesions that typically resolve spontaneously . the clinical course is completely benign , but the high risk of misinterpreting these lesions as malignant owing to its rapid growth , high cellularity and high mitotic activity on histology has been well documented . these lesions are also a major diagnostic pitfall in fine needle aspiration cytology ( fnac ) . as fnac of soft tissue lesions is becoming more widely accepted , it is important to recognize the cytological features of these reactive lesions . a 65-year - old man presented with a hard mass measuring 4  3 cm in the supraclavicular region . the smears were moderately cellular and showed proliferative spindle cells among the skeletal muscle fibers . the mass was excised . grossly , the mass was grey - white and measured 32 cm . on histopathology , there were skeletal muscle fibers and fibro - collagenous tissue with chronic inflammatory cells , proliferating fibroblasts and giant cells . ( a ) smear shows spindle cells among skeletal muscle fibers ( h and e , 100 ) . ( c ) ganglion - like cells ( pap , 400 ) a 29-year - old man presented with a firm mass measuring 2.2  2 cm in the upper neck of one week duration . fnac was done . the aspirate was cellular and showed a polymorphous population of isolated and sheets of spindle cells with inflammatory cells consisting of lymphocytes , plasma cells , eosinophils and neutrophils . the nuclei of some of the cells were slender with pointed ends , while others had round to oval nuclei , with evenly distributed fine chromatin . a few muscle giant cells and ganglion - like cells of triangular to polyhedral shapes a 65-year - old man presented with a hard mass measuring 4  3 cm in the supraclavicular region . the smears were moderately cellular and showed proliferative spindle cells among the skeletal muscle fibers . the mass was excised . grossly , the mass was grey - white and measured 32 cm . on histopathology , there were skeletal muscle fibers and fibro - collagenous tissue with chronic inflammatory cells , proliferating fibroblasts and giant cells . ( a ) smear shows spindle cells among skeletal muscle fibers ( h and e , 100 ) . a 29-year - old man presented with a firm mass measuring 2.2  2 cm in the upper neck of one week duration . the aspirate was cellular and showed a polymorphous population of isolated and sheets of spindle cells with inflammatory cells consisting of lymphocytes , plasma cells , eosinophils and neutrophils . the nuclei of some of the cells were slender with pointed ends , while others had round to oval nuclei , with evenly distributed fine chromatin . a few muscle giant cells and ganglion - like cells of triangular to polyhedral shapes the potential of fnac as a diagnostic tool in the evaluation of soft tissue lesions is becoming increasingly evident as usage becomes widespread . benign spindle cell proliferations of soft tissue can be exceptionally difficult to correctly interpret and subclassify using fna - based smears . pseudosarcomatous soft tissue lesions , are further , a major diagnostic pitfall in the fnac of spindle cell lesions . the dilemma is compounded when such pseudosarcomatous lesions occur in uncommon sites or has unusual characteristics . nf , pf and pm are a closely related group of self - limiting , benign proliferative lesions of fibroblasts and myofibroblasts of unknown cause . the fnac features of nf and pf are essentially the same , except that pf shows lower cellularity , more collagen fragments , and abundant ganglion - like cells . cytologically , the aspirates are moderately cellular with a mixture of isolated cells and sheets of closely packed spindled fibroblast - like cells . pm differs from nf in two ways : ( 1 ) the proliferative spindle cells are situated among skeletal muscle tissue and ( 2 ) the giant ganglion - like cells are more abundant . the reasons for misdiagnosis in the first case were : ( 1 ) the age of the patient and location of the lesion ( 2 ) failure to recognize the importance of spindle cells within the skeletal muscle fibers and ( 3 ) misinterpretation of muscle giant cells as normal skeletal muscle fibers and ganglion - like cells with reactive atypia as malignant cells . nf is the most common pseudosarcomatous proliferative lesion of soft tissues that seldom recurs . unlike soft tissue neoplasms which require surgical excision for treatment , it is well established that pseudosarcomatous proliferative lesions of soft tissue usually present as small , superficial nodules with rapid growth and short duration in contrast to the fairly deep , large masses and long duration of sarcomas . cytologically , a polymorphic pattern of cells , high cellularity , abundant isolated cells and ganglion - like cells with benign looking nuclei are the most characteristic features . inflammation varies from minimal to marked and consists of neutrophils , lymphocytes , eosinophils , histiocytes and/or multinucleated giant cells . given its variable morphological appearance , ranging from myxoid to fibrous , nf can be difficult to distinguish from soft tissue neoplasms and nf is considered as the first diagnostic pitfall in the fnac of spindle cell lesions . in our case , although the site in the neck was rare , a short clinical history , the correct identification of reactive nature of the spindle cells , ganglion - like cells and muscle giant cells in an inflammatory background was crucial in making the correct diagnosis . spontaneous resolution provided objective evidence that the fnac diagnosis was correct , thus avoiding unnecessary surgery . these studies can be done on fresh aspirate smears , destained slides or cell block material . since nf can exhibit fibrohistiocytic , as well as myofibroblastic differentiation , smooth muscle actin and cd68 can be useful . in conjunction with clinical course , fnac is a helpful diagnostic tool to differentiate pseudosarcomatous proliferative lesions of soft tissue from true sarcomas . when the clinical data and fnac features are typical of nf , pf or pm , the patient should be managed nonsurgically first with follow - up . if regression does not occur within four to eight weeks , surgery should be performed . . the cytological diagnosis of these lesions can be challenging . in spite of atypical nuclei , fine chromatin , smooth nuclear membranes , giant cells and inflammatory cells
pseudosarcomatous lesions are reactive proliferative lesions of the soft tissue , that are likely to be misdiagnosed as malignant , based on clinical and histological features . 
 the most common lesions are nodular fasciitis , proliferative fasciitis , proliferative myositis and myositis ossificans . 
 these rapidly growing soft - tissue lesions can represent a variety of diagnoses involving radically different treatment modalities . 
 accurate diagnosis is important to avoid unnecessary and often mutilating surgery . 
 we report two cases to illustrate the importance of correct identification of these lesions by fine needle aspiration cytology .