superficial leiomyosarcomas are rare malignant tumors that account for only 510% of all soft tissue sarcomas .
they can be subdivided into two types according to its primary site of origin : deep subcutaneous and superficial cutaneous types .
primary cutaneous leiomyosarcoma ( pcl ) is a rare subtype with few isolated case reports and occasional case series described in the literature .
we report the clinical , histopathological and immunohistochemical findings in a 70-year - old male patient with pcl arising in the right leg .
a 70-year - old male patient presented with a painful nodule in the right leg , which had been progressively increasing in size for 4 months . on palpation , an irregular , firm , tender exophytic swelling , measuring 5 cm  5 cm , with overlying skin showing ulceration was noted on the lateral aspect of the lower one third of the right leg [ figure 1a ] .
his past history was significant of a trauma and subsequent non - healing ulcer formation at the same site in the right leg .
( a ) clinical photograph showing an irregular , exophytic swelling , measuring 5 cm  5 cm , with overlying skin showing ulceration on the lateral aspect of the lower one - third of the right leg .
( c ) gross photograph showing greyish white , solid , homogenous and fleshy cut surface of the irregular tumor mass measuring 5 cm  5 cm  2.5 cm systemic examination and investigations , including complete blood count , fasting blood sugar level , liver function test and renal function test , were within normal limits .
hepatitis b virus surface antigen and human immunodeficiency virus enzyme - linked immunosorbent assay were non - reactive .
a clinical diagnosis of squamous cell carcinoma was considered and fine needle aspiration cytology of the swelling was requested .
fine needle aspiration cytology of the same was reported as a spindle cell neoplasm with suspicion of malignancy .
the swelling was excised with a 5 cm resection margin and submitted for histopathological examination [ figure 1b ] .
gross inspection revealed a grey brown , irregular , nodular soft tissue mass , measuring 5 cm  5 cm  2.5 cm and partly covered with skin .
the cut surface of the mass was greyish white , solid , homogenous and fleshy [ figure 1c ] .
the neoplasm was composed of bundles of elongated spindle cells arranged in interlacing fascicles , with intensely pink , fibrillary cytoplasm and pleomorphic nuclei with coarse irregularly dispersed chromatin .
mitosis , including atypical , amounting to 22 mitotic figures per 10 high power fields and multinucleate tumor giant cells , was evident .
( a ) light microscopy revealed a dermal neoplasm with extension into the subcutaneous tissue ( h & e , 40 ) .
( b ) neoplasm composed of interlacing fascicles of elongated spindle cells ( h & e , 100 ) .
( c ) tumor cells are spindle shaped with intensely pink , fibrillary cytoplasm and pleomorphic hyperchromatic nuclei frequently exhibiting atypical mitosis ( black arrow ) ( h & e , 400 ) .
( d ) tumor cells with markedly pleomorphic nuclei and multinucleate tumor giant cell ( inset ) ( h & e , 400 ) a provisional diagnosis of spindle cell malignant neoplasm of the skin , which typically includes a host of diagnostic possibility , namely fibrosarcoma , leiomyosarcoma , malignant peripheral nerve sheath tumor , monophasic synovial sarcoma , malignant fibrous histiocytoma and spindle cell variant of squamous cell carcinoma , was considered and immunohistochemistry was advised for confirmation .
on immunohistochemistry , tumor cells showed strong immunopositivity for vimentin , muscle - specific actin ( msa ) , smooth muscle actin ( sma ) , caldesmon and desmin and negative for pancytokeratin , epithelial membrane antigen ( ema ) , myogenin , cd34 and s-100 protein [ figure 3 ] .
immunohistochemical staining : neoplastic cells showing positive immunostaining for ( a ) vimentin ( vimentin , 400 ) , ( b ) caldesmon ( caldesmon , 400 ) , ( c ) muscle - specific actin ( msa , 400 ) and ( d ) smooth muscle actin ( sma , 400 ) based on the immunophenotypic features , a final diagnosis of pcl was rendered .
the patient is currently on periodic follow - up since 1 year and no recurrence or metastasis has been identified so far .
although pcl most commonly arises in the extremities , particularly hair bearing surfaces , it may occur at any anatomic site on the body .
most case series described in the literature report a predilection for the middle aged to elderly male . in a large case series reported by fields and helwig ,
95% of the patients with pcl presented with a solitary nodule with a median size of 1.8 cm at presentation .
pain was reported by 24% of their patients at presentation , whereas pain could be elicited on pressure in an additional 27% of the patients .
histologically , pcl is characterized by a poorly circumscribed proliferation of interwoven fascicles of spindle shaped atypical myomatous cells that merge with a collagenous stroma .
mitosis , equivalent to one or more per 10 high - power fields , high cellularity and bizarre myomatous cells are the generally accepted criteria for malignancy .
described two growth patterns : a nodular pattern characterized by high cellularity , prominent nuclear atypia , conspicuous mitosis and a diffuse pattern that is less cellular , well differentiated and inconspicuous mitosis .
morphologic differential diagnosis includes a galaxy of other malignant spindle cell neoplasms , namely desmoplastic malignant melanoma , spindle cell synovial sarcoma , spindle cell angiosarcoma , fibrosarcoma , malignant fibrous histiocytoma and malignant peripheral nerve sheath tumor .
cutaneous leiomyosarcoma often exhibit immunophenotypic polymorphism , thereby mandating the use of a large panel of antibodies .
however , none of these markers is absolutely specific for smooth muscle , and positivity for two of these markers is more supportive of leiomyosarcoma .
jensen et al . identified several poor prognostic factors , namely tumor size 5 cm , acral location , deep localization with fascia involvement and high histological grade .
cutaneous leiomyosarcomas have fewer incidences of local recurrence ( 30 - 50% ) and negligible potential for distant metastases ( 010% ) . in contrast
, subcutaneous leiomyosarcomas may develop local recurrence in about 4060% and distant metastasis in 2060% of patients .
a wide local excision with a 35 cm margin is usually an effective treatment for pcl .
, pcl is a rare entity that must be borne in mind when encountered with a malignant spindle cell neoplasm of the skin and usually requires a panel of immunohistochemical markers to distinguish it from other cutaneous malignancies with spindle cell morphology .
 primary cutaneous leiomyosarcoma ( pcl ) is an exceedingly uncommon malignant superficial soft tissue sarcoma with a predilection for middle - aged to elderly male . 
 morphologic differential diagnosis includes a host of other malignant spindle cell neoplasms , thereby necessitating the use of a panel of immunohistochemical markers to arrive at a definitive diagnosis . 
 we report a case of pcl arising in the right leg of a 70-year - old male . 