Perianal superficial CD34-positive fibroblastic tumor: A case report

BACKGROUND Superficial CD34-positive fibroblast tumors (SCPFTs) are newly recognized fibroblast and myofibroblast tumors representing intermediate tumors. To the best of our knowledge, fewer than 50 cases have been reported. Perianal SCPFT has not been previously reported. CASE SUMMARY A 55-year-old man was hospitalized upon discovering a painless perianal lump 10 d prior. Physical examination showed a lump of approximately 3 cm x 4 cm in the 7 to 8 o'clock direction in the perianal area. Perianal abscess was considered the primary diagnosis. Lump removal surgery was performed under epidural anesthesia. Postoperative pathology showed a well-circumscribed, soft tissue-derived, spindle-cell tumor with strong CD34 positivity by immunohistochemistry. The final diagnosis was perianal SCPFT. There were no complications, and the patient was followed for more than 8 mo without recurrence or metastasis. CONCLUSION We report a case of perianal superficial CD34-positive fibroblast tumor. This rare mesenchymal neoplasm has distinctive histomorphology, which is important for diagnosis. Comprehensive consideration of clinical information, imaging, histology, and immunohistochemistry is important for diagnosis.