A 32-year-old female came with a chief complaint of swelling over the right side of the back since last year. It was gradual in onset, and there was a progressive increase in the size of the swelling. The patient complained of pain over the swelling. She had a history of cyst excision done four years back from the same site.
On local examination, a palpable lump of size 3 cm x 3 cm was present over the right side of the back (Figure 1). The swelling was firm, non-tender, and non-mobile. There were no areas of redness over the swelling. There was no local increase in temperature or any skin discoloration around the swelling. Systemic examination revealed no abnormalities.
Timeline of the current episode
The patient had swelling on the right side of the back for one year. Swelling gradually increased in size, involved the skin over the back, and caused pain and discomfort to the patient during the previous week. The patient had a similar complaint of cystic swelling over the same site four years back, which she had got excised. The patient exhibited generalized weakness. There was no history of discharge from the swelling. The patient does not have diabetes mellitus, asthma, tuberculosis (TB), hypertension, or any other known diseases.
Diagnostic assessment
The USG local region revealed a well-defined hypo-echoic lesion of size 3.8 cm x 2.1 cm x 3.5 cm in the subcutaneous area in the right lumbar region. It showed posterior acoustic enhancement and multiple septa within. Color Doppler imaging revealed a significant vascularity. The patient was provisionally diagnosed with peripheral nerve sheath tumor. USG-guided fine needle aspiration cytology (FNAC) was performed. 
Operative procedure
Wide local excision of the tumor was performed under general anesthesia, and the specimen (Figure 2) was sent for histological examination.
Diagnosis
USG-guided fine-needle aspiration (FNA) smears revealed moderate cellularity (Figure 3), showing a cluster and dissociated singly scattered cells with ovoid nuclei and ill-defined cytoplasmic borders (Figure 4). A few plump and slender spindle cells were observed (Figure 5). An impression of cytological features in favor of a spindle cell tumor was made.
The excised tumor was subjected to a histological examination. It was a single globular specimen with attached fibroadipose tissues and skin (Figures 6, 7). The total dimensions of the specimen were 8 cm x 3.5 cm x 2.5 cm. The tumor was globular and white in color. The cut surface was homogenous white, soft to firm, and measured 3.5 cm x 3.5 cm x 3.5 cm in size.
On microscopy, sections from different areas revealed a nodular mass composed of a proliferation of mostly uniform, medium-sized spindle cells with a storiform or cartwheel pattern of growth (Figures 8, 9) placed in the dermis and extending into the subcutaneous adipose tissue (Figure 10). It was separated from the epidermis by a grenz zone. Adnexal structures were also embedded in the tumor. The overlying epidermis appeared normal (Figure 11). The tumor infiltrated the subcutaneous adipose tissue in a honeycomb pattern. Histological features suggestive of dermatofibrosarcoma protuberans were observed.
Follow-up and outcomes
Post-operation, the patient was relieved of acute symptoms of pain and swelling over the right side of her back. Her discomfort had subsided. Overall, the patient was doing quite well after the surgical intervention.