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Título

MAMMARY-TYPE MYOFIBROBLASTOMA OF THE INGUINAL REGION: A RARE DIFFERENTIAL DIAGNOSIS OF SPERMATIC CORD TUMOR

Introdução, Material, Método, Resultados, Discussão e Conclusões

Case report
A 37-year-old male presented with a 3-month history of left inguinal bulging. It was growing slowly, without inflammatory or constitutional symptoms. There was no report of other pelvic abnormalities.
At physical examination, left inguinal mass was palpable. Lesion was soft, non-pulsatile, movable, with approximate size of 5cm. Testicles were topic and lesion had intimated contact with spermatic cord, moving along with its handling.
Ultrasound (US) revealed an hyperechogenic, heterogeneous and well-defined oval lesion, measuring about 5.0x4.4cm. CT scan of the pelvis showed a mass anterior to the inguinal canal, with smooth attenuation and heterogeneous enhancement to intravenous contrast.
US-guided core-needle biopsy was performed. Histopathological evaluation found a spindle cell process without any histological atypia; immunohistochemistry analysis showed a positive staining for CD34 and desmin and negative staining for S-100 and smooth muscle actin. Diagnosis of mammary-type myofibroblastoma (MTMF) was made.
Surgical excision was performed. A well circumscribed tumor was identified at inguinal canal, adjacent to spermatic cord without signs of invasion, so that it could be preserved. Histopathological evaluation of surgical specimen confirmed diagnosis, with negative surgical margins.
Discussion:
MTMF is a mesenchymal tumor, first described as a spindle cell tumor of the breast. This tumor has a wider anatomic distribution. Inguinal region is the most common extra-mammary site. Based on retrospective series, no patients with MTMF developed recurrence or metastases.
MTMF is characteristically composed of uniform spindle cells, typically expressing desmin and CD34. There is variable expression of actin. S-100 protein and cytokeratins are typically negative.
Imaging of inguinal region can detect solid inguinal tumors, but cannot accurately distinguish between benign or malignant. Core biopsy can be useful for diagnosis and ruling out sarcoma.
Based on indolent characteristics of MTMF, simple excision can be considered an adequate therapy. In this case, we preserved spermatic cord as we knew diagnosis preoperatively.
Conclusion:
MTMF is a rare benign tumor. Urologists and surgical oncologists should be aware of this entity as a differential diagnosis of spermatic cord tumors, because simple surgical excision has excellent prognosis, virtually no recurrence and preservation of spermatic cord.

Palavras Chave

Case report; Inguinal tumor; Mammary-type myofibroblastoma