Dermatofibrosarcoma protuberans (DFSP) involving oral cavity in child.

Abstract

Introduction

DFSP is a rare low-grade spindle cell malignancy (<0.1% of all malignancies, <1% of soft tissue sarcomas). Majority of these cutaneous tumors occur in 20-50 year-olds and are slow growing, asymptomatic without ulceration. Most common sites of involvement are trunk and extremities with 10- 15% in head and neck. Oral cavity DFSP is extremely rare with 6 documented cases in literature (age range: 44-72 years; 4M:2F, 2 vermillion lip; 4 buccal mucosa). DFSP diagnosis is based upon CD34 expression and COL1A1:PDGFB fusion identification.

Methods and Materials

5 year-old male presented for annual dental examination to pediatric dentist. Of significance, a nontender, submucosal enlargement with intact mucosal surface of the right hard palate was noted. Initial biopsy impression at originating institution was infantile fibrosarcoma. Additional immunohistochemical and gene fusion detection studies were performed at the consulting institution.

Results

Consultative review demonstrated low-grade spindle cell tumor (Positive for CD34; Negative for PanTRK, STAT6, ALK, Desmin, MyoD1, Myogenin). Presumptive DFSP diagnosis was rendered. COL1A1:PDGFB fusion identification (RT-PCR) confirmed DFSP diagnosis. Patient underwent conservative surgical resection with negative margins. Resection specimen demonstrated fleshy mass extensively involving submucosa with intact mucosa.

Conclusion

Indolent asymptomatic clinical presentation of DFSP tends to result in delayed diagnosis. This low grade spindle cell tumor may be mistaken for other benign and malignant spindle cell tumors (deep fibrous histiocytoma, dermatofibroma, dermatomyofibroma, perineurioma, neurofibroma, leiomyoma, solitary fibrous tumor, infantile fibrosarcoma, conventional fibrosarcoma, leiomyosarcoma, spindle cell melanoma). DFSP may be differentiated from other spindle cell tumors based on histopathologic and immunophenotype features (especially positive CD34, with negative immunostaining characteristic for other entities), and confirmed by identifying COL1A1:PDGFB fusion. Metastatic disease is rare (<1%). DFSP transformation to high-grade fibrosarcoma with metastatic potential may occur in minority of cases.