Dermatofibrosarcoma protuberans at an uncommon site.

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive, cutaneous, malignant tumor characterized by high propensity for local relapse and low metastatic potential. It is seen mainly in the age group of 6-65 years over the trunk and extremities. Immunohistochemically it diagnosed by marker human progenitor cell Ag CD 34. Herein, we present a 40-year-old male with DFSP over the pubic area and extending up to the proximal penile shaft. The biopsy revealed intervening bundles of spindle-shaped cells in the dermis and the diagnostic marker human progenitor cell Ag CD 34 was positive. The patient underwent wide local surgical resection.

What was known?

DFSP is locally aggressive fibrous tumor affecting the trunk and extremities.

Introduction

Dermatofibrosarcoma protuberans (DFSP) is a rare slow growing skin tumor with tendency to local recurrence.[1] It is a locally aggressive fibrous tumor but rarely shows metastasis to local lymph nodes or distant sites. Hallmark of the disease is characteristic arrangement of spindle-shaped tumor cells in dermis.[2] Positive staining for CD34 on immunnohistochemistry is also pathgnomic.[3] Wide and deep local excision is the treatment of choice. DFSP is rare and represents 1-6% of all soft tissue sarcomas. The commonly affected areas are the trunk, extremities, scalp, and neck. Only one case has been reported in the suprapubic area. This report describes a case of suprapubic DFSP involving the proximal penile shaft.

Case Report

A 40-year-old male, farmer by occupation, presented with complaints of foul smelling lesions over the pubic region since 7 months. He was symptomless for the first 6 months after history of similar lesions 1 year back, which were excised. There was no history of sexually transmitted infection and diabetes mellitus. General and systemic examination was normal.

Examination revealed three erythematous fleshy nodules measuring about 3-4 cm in size with foul smelling discharge over the pubic area extending to the proximal shaft of the penis [Figure 1]. The surface of the swelling showed multiple protruberations with nodules, which were firm, non tender, freely mobile over the underlying structure. The distal penile shaft and scrotum were spared. No regional lymphadenopathy was seen.

Figure 1

Three erythematous fleshy nodules measuring about 3-4 cm in size over the pubic area extending to the proximal shaft of the penis

All routine investigations were within normal limits. Test for human immunodeficiency virus (HIV), syphilis, hepatitis B were negative. Biopsy of the lesion revealed flattening of epidermis in one area and elongated rete pegs in the other parts. In the dermis, a tumor composed of intervening bundles of spindle-shaped cells was seen [Figure 2]. The immunohistochemical marker human progenitor cell Ag CD 34 was positive.

Figure 2

Histopathology shows characteristic spindle shape tumor cells in the dermis (H and E × 10)

A diagnosis of DFSP was made and treated by wide local excision with 2 cm of free margin. [Figure 3].

Figure 3

Wide local excision with 2 cm of free margin

Discussion

DFSP is a locally aggressive, cutaneous, malignant tumor characterized by high propensity for local relapse and low metastatic potential. DFSP have been reported in the literature as early as 1890, Darier and Ferrand first described it in 1924 as a distinct cutaneous disease entity called progressive and recurring dermatofibrosarcoma.[4] Hoffman officially coined the term DFSP in 1925.[5] DFSP represents 1-6% of all soft tissue sarcomas.[6]

Age of onset of the disease ranges from 6 to 65 years.[1] It usually involves the trunk, proximal extremities and the scalp. Head, necks and genitals are rarely involved,[7] whereas in our case the proximal penile shaft was involved. The tumor tends to appear first as a single firm, fibrous nodule in skin, with a pink or violaceous hue, which is freely mobile on deeper structures. It enlarges by expansile growth, while the periphery of tumor infiltrates the adjacent skin and subcutaneous tissue. Differential diagnosis in the initial stages should include lipomas, epidermal cysts, keloid, and nodular fasciitis. In late stages, when it becomes protuberant, it should be differentiated from pyogenic granuloma and other soft tissue sarcomas.

Immunohistochemically, most DFSP stain positively for CD34,[3] which was also positive in our case. Histopathologically it, is characterized by the arrangement of spindle-shaped tumor cells in a “cartwheel” pattern,[2] cytologically monomorphous bland spindle cells, with a characteristic finger-like, honeycomb pattern of infiltration into the subcutaneous fat.

The treatment of choice is wide surgical excision ensuring adequate margins of 3-5 cm, followed by immediate reconstruction.[8] Radiotherapy and chemotherapy have been tried with limited success. The significant prognostic factor for relapse is considered to be the extent of the initial resection as close margins that is less than 2 cm shows a statistically significant positive correlation with recurrence.[9] Mohs micrographic surgery is the precise margin controlled approach for excision of DFSP.[10]

What is new?

Involvement of proximal penile shaft with suprapubic region by DFSP.