Case History: 40 YO male with PMH of HIV and Hepatitis B, presents with a painful soft tissue growth to the medial ankle of several years duration. The mass fluctuates in size and there is no known history of trauma similar masses elsewhere. The mass persists despite conservative treatment including: steroid injection, cordran tape, and PT. After exhausting conservative measures, patient prefers to have surgical excision.
Methods: Prior to surgical excision, diagnostic exams were obtained. X-rays were obtained to rule out osseous abnormalities. MRI study diagnosed the mass as giant cell tumor with repeat MRI findings of “indeterminate consisting of an ill-defined subcutaneous soft tissue mass at the medial aspect of the ankle which likely represented chronic inflammatory processes versus organized hematoma/scar, although low-grade soft tissue malignancy could not be excluded." Patient was next scheduled for excisional biopsy. Surgery however was complicated by indeterminate intraoperative frozen section results resulting in closure of surgical site without excision of the mass. Once the final pathology report returned with the diagnosis of collagenous fibroma, patient was scheduled for complete excision. Intraoperatively, the soft tissue mass was noted to be encapsulated by numerous vessels and nerves with pedicles, making the excision complicated. However, successful excision of the mass was achieved with clear margins based on the pathology report and a final diagnosis of collagenous fibroma.
Results: Post-operatively, patient remains pain free and has been able to resume recreational activities. Soft tissue masses can be challenging to treat especially with unknown etiology, and indeterminate imaging and diagnostic studies.
Conclusion: Understanding the histological origin of collagenous fibroma can help practitioners better provide treatment. This case teaches us proper management of these indeterminate masses that may resemble neoplasm.