superficial acral fibromyxoma ( saf ) is a rare , distinctive benign soft tissue tumor with a predilection for the hands and feet . it often involves the fingers and toes , with the big toe being most frequently affected . to date , there is only one case that has been diagnosed on cytological features . we herein report a case of saf primarily diagnosed by fine needle aspiration cytology ( fnac ) and confirmed by histopathological study . a 27-year - old healthy female presented with an asymptomatic , globular swelling over the right great toe since 2 years . hemispherical firm , non - tender nodule in the subungual region with no involvement or deformity of the nail plate [ figure 1 ] . hemispherical nodule in the subungual region of the right great toe fine needle aspiration ( fna ) yielded mucoid material , which showed benign plump oval to spindle cells arranged in groups , sheets and cohesive clusters in a background of myxoid material with interspersed thin - walled capillaries . the cells had indistinct cytoplasm and blunt oval to spindle - shaped nuclei [ figure 2 ] . with these , a diagnosis of saf was suggested and an en block excision biopsy was performed and subjected to histopathological examination . fine needle aspiration smear showing benign plump oval to spindle - shaped cells in groups , sheets and cohesive clusters in a background of myxoid material and insert showing the histopathological section , confirming the cytological findings ( pap , 400 ) grossly , the specimen consisted of a skin - covered tissue , which on cut - section revealed a well - circumscribed grey - white lesion in the subcutis . on microscopy , there was a hyperkeratotic epidermis and a dermal tumor composed of spindle and stellate cells with random , loose storiform and fascicular patterns that were embedded in abundant myxocollagenous stroma that showed alcian blue positivity [ figure 3 ] . dermal tumor composed of spindle and stellate cells arranged in loose storiform and fascicular patterns and embedded in an abundant myxocollagenous stroma ( h and e , 100 ) it is not listed in the current world health organization 's pathology and genetics of skin tumors , but was listed in the armed forces institute of pathology 's non - melanocytic tumors of the skin ( atlas of tumor pathology ) . most cases occur in the subungual or periungual regions , with rare cases occurring on the ventral surface of the digit . few cases located close to the nail caused deformity of the nail and affected the underlying bone , but there was no evidence of systemic involvement . majority of the patients were males , with a male to female ratio of 1.3:1 , and they belonged to an age range of 14 - 91 years with a mean of 48.2 years and a median of 49.0 years . as in the present case the tumor presented as a painless solitary mass with an average size of 17.8 mm , few cases that presented with pain were associated with history of trauma . roentgenographic examination in most cases showed no bony alterations , while exceptional cases showed marginal erosion of distal phalanx or depression or scalloping of the underlying bone . fna yielded mucoid material and showed loose clusters of benign spindle cells in a myxoid background . the lesions with no involvement of the underlying nail plate or bone when excised completely revealed a dome - shaped , well - circumscribed tumor in the dermis as seen in the present case . saf are generally unencapsulated , but , in the present case , the tumor displayed a vague lobular pattern that compressed the surrounding tissue giving a partially pseudocapsulated appearance . the tumor was composed of spindle- to stellate - shaped cells arranged in a vague storiform pattern embedded in a myxoid matrix . multinucleated stromal cells may be present , but nuclear atypia and mitotic figures are rare . previous studies have shown that the myxoid matrix is highlighted by the alcian blue ( ph 2.5 ) stain . characteristically , tumor cells show positivity for vimentin , cd-34 , cd-99 , ema and cd10 and are negative for s-100 protein . expression of nestin ( a marker of multipotent stem cells ) or cd-10 ( co - expressed by mesenchymal cells in the nail unit ) points to the cell of origin as being either the multipotent dermal stem cells or the mesenchymal cells in the nail unit . in an ultrastructural study by pasquinelli et al . , the tumor cells were found to be composed of cytoplasmic intermediate filaments and numerous cisternae of rough endoplasmic reticulum , confirming the fibroblastic nature of the tumor cells . malignant behavior or metastasis has not been reported , but the tumor may persist or recur if inadequately excised . it is observed that all recurrent tumors have positive margins on initial biopsy or on subsequent excision . a pre - operative correct diagnosis of saf by fna cytology is thus essential to plan a complete surgical excision that avoids further recurrence . the differential diagnosis for saf includes myxoid neurofibroma , fibroma of tendon sheath , glomus tumor , superficial angiomyxoma , acral fibrokeratoma , sclerosing perineuroma , cutaneous myxoma , myxoid fibrous histiocytoma and dermatofibrosarcoma protuberans . myxoid neurofibroma often has a neural appearance , with no increase in vascularity , and has a characteristic s-100 positivity . fibroma of the tendon sheath has an attachment to the tendon sheath and has only sparse stellate cells in a fibrocollagenous matrix . the glomus tumor is a very painful dermal nodule composed of sheets or nests of uniform round cells with immunoreactivity for vimentin and smooth muscle actin . superficial angiomyxomas are dermal or subcutaneous nodules that can affect any part of the body , especially the head , neck and trunk . these tumors , in addition to having spindle - shaped and stellate cells in a basophilic matrix , have an epithelial component . acral fibrokeratoma are exophytic , solitary lesions with a hyperkeratotic epidermis and a core of thick , vertically oriented collagen bundles . the tumor is paucicellular and ema negative . sclerosing perineuroma is composed of dense collagen with small , epitheloid and spindle - shaped cells arranged in cords , trabecular and onion - skin patterns , which make them distinct from saf . cutaneous myxoma has an epithelial component in addition to the fibroblasts and prominent capillaries in a mucinous matrix . myxoid fibrous histiocytoma contain spindle cells in a storiform pattern that show positivity for factor xiiia antigen and the myxoid area is not as abundant as in saf . dermatofibrosarcoma protuberans is a dermal tumor composed of cells arranged in storiform pattern and is often seen extending into the subcutis . awareness of this entity is helpful in distinguishing this lesion from other myxoid soft tissue tumors and in proper management of these cases .
superficial acral fibromyxoma ( saf ) is a rare , distinctive benign soft tissue lesion that often involves the fingers and toes , with the great toe being the most frequently affected site . 
 we report a case of saf diagnosed by fine needle aspiration cytology and confirmed by histopathology . 
 the pre - operative cytological diagnosis will help the surgeon to plan for a wider excision that prevents recurrence .