陰囊細胞型血管纖維瘤偽裝為副睪丸腫瘤：病例報告與文獻回顧

黃君平、高建璋、曹智惟、楊明昕

國防醫學大學三軍總醫院外科部泌尿外科

Scrotal Cellular Angiofibroma Mimicking a Paratesticular Neoplasm: Case Report and Literature Review

Chun-Ping Huang, Chien-Chang Kao, Chih-Wei Tsao, Ming-Hsin Yang

Division of Urology, Department of Surgery, Tri-Service General Hospital, National Defense Medical University, Taipei 114024, Taiwan

Introduction: Cellular angiofibroma (CAF) is a rare benign mesenchymal tumor that typically arises in the superficial soft tissues of the genital region. Although it most commonly occurs in the vulvovaginal area of women, it can also develop in the inguinoscrotal region of elderly men. Due to overlapping clinical, radiologic, and histopathologic features with other spindle-cell tumors of the paratesticular region, including well-differentiated liposarcoma, accurate diagnosis can be challenging.

Case Presentation: A 71-year-old man with a prior history of descending colon adenocarcinoma, previously treated with left hemicolectomy followed by adjuvant FOLFOX chemotherapy in 2015, presented with nausea, coffee-ground emesis, persistent hiccups, and epigastric discomfort for one week. On examination, he had diffuse abdominal tenderness along with swelling of the left hemiscrotum. Laboratory studies revealed leukocytosis, while tumor markers, including AFP, CEA, β-HCG, and LDH, were within normal limits.

Computed tomography of the abdomen demonstrated findings consistent with small bowel obstruction, most likely related to postoperative adhesions. An incidental 6.5-cm mass was also noted in the perineal/scrotal region, showing heterogeneous contrast enhancement and raising suspicion for a malignant process. Surgical removal of the lesion revealed a well-demarcated mass measuring 6 × 5 × 5 cm that was separate from the testis.

Microscopic evaluation demonstrated spindle-shaped cells embedded in a fibrous stroma with numerous hyalinized vascular channels. Immunohistochemical analysis showed overexpression of MDM2, focal positivity for S100, and loss of RB protein expression, findings consistent with cellular angiofibroma. The patient’s postoperative course was uneventful.

Discussion: One of the major diagnostic challenges in this case was distinguishing cellular angiofibroma from other benign and malignant spindle-cell tumors of the paratesticular region. The presence of a relatively large scrotal mass in an elderly patient with a prior history of colorectal adenocarcinoma initially raised concern for metastatic disease or a primary malignant soft-tissue tumor, such as liposarcoma of the spermatic cord. Furthermore, the histologic appearance of bland spindle cells within a fibrous stroma and prominent small- to medium-sized blood vessels overlaps with several other mesenchymal neoplasms, including spindle cell lipoma, solitary fibrous tumor, angiomyofibroblastoma, and aggressive angiomyxoma. These entities share similar morphologic and, in some cases, immunohistochemical features, which can complicate diagnosis. Accurate diagnosis requires careful integration of tumor location, circumscribed growth pattern, vascular architecture, and a panel of immunohistochemical stains.

In this case, the well-circumscribed lesion composed of bland spindle cells with characteristic vascular features, along with immunohistochemical findings demonstrating MDM2 expression, focal S100 staining, and loss of RB protein expression, supported the diagnosis of cellular angiofibroma and helped exclude more aggressive neoplasms.

Conclusion: This report underscores scrotal cellular angiofibroma as a rare but important consideration in the differential diagnosis of paratesticular masses in elderly men. Although the lesion initially raised suspicion for malignancy due to its size and clinical context, the benign nature of the tumor was confirmed by characteristic histopathologic features, normal serum tumor markers (AFP, β-HCG, LDH, and CEA), and the loss of RB protein expression. Recognizing this entity is important to prevent unnecessarily extensive surgical treatment, as complete local excision is typically curative.