Imaging Findings and Histologic Appearances of Alveolar Soft Part Sarcoma in the Prostate: A Case Report and Review of the Literature

Computed tomography, magnetic resonance imaging, and F-deoxyglucose positron emission computed tomography/computed tomography findings of alveolar soft part sarcoma with calcification in the thigh: A case report

BACKGROUND

Alveolar soft part sarcoma (ASPS) is an extremely rare malignant sarcoma, accounting for less than 1% of all soft-tissue sarcomas. However, limited information is available on multimodal imaging [computed tomography (CT), magnetic resonance imaging (MRI), and positron emission computed tomography/computed tomography (PET/CT)] of ASPS.

CASE SUMMARY

This study reports a case of a 35-year-old female patient with ASPS of the left thigh with lung metastasis. The patient presented with a 1-year history of a palpable mass in the lower extremity, which exhibited rapid growth for 3 wk. CT, MRI, and F-deoxyglucose PET/CT examinations were performed. CT showed a slightly hypodense or isodense mass with patchy calcifications. On MRI examination, the mass manifested hyperintensity on T1-weighted, T2-weighted, and diffusion-weighted images with some signal voids. PET/CT images demonstrated an intensely hypermetabolic mass in the left thigh and hypermetabolic nodules in lungs.

CONCLUSION

ASPS should be considered as a possible diagnosis when a slow-growing mass is detected in the soft tissue of the extremities, with hyperintensity and numerous signal voids on T1-weighted, T2-weighted, and diffusion-weighted images and intense F-deoxyglucose uptake on PET/CT. ASPS can have calcifications on CT.

Alveolar soft part sarcoma mimics prostate cancer metastasis

A 61-year-old man presented to the oncology clinic with Gleason 9 (4 + 5) prostate cancer. Staging CT showed multiple nodules in both lungs. Since the lung lesions were too small for biopsy, he was started on anti-androgen therapy for suspected metastatic, hormone-sensitive prostate cancer. While his prostate-specific antigen decreased from 32 to <0.1 ng/ml, the multiple lung lesions showed no response on subsequent imaging. The patient presented during follow-up with severe right leg pain, at which time magnetic resonance imaging revealed a large, hyperintense mass in the femur. The mass was resected along with two lung nodules, with pathology demonstrating metastatic alveolar soft part sarcoma. This serves as an important reminder that lesions suspicious for metastases may be due to cancers of multiple primary origins, particularly if the pattern of metastasis is atypical or there is varied response to therapy.

Alveolar Soft Part Sarcoma of Urinary Bladder Occurring as a Second Primary Malignancy: A Case Report and Literature Review

We report a case of bladder alveolar soft part sarcoma in an 18-year-old Thai male patient who had been treated with testicular radiation and systemic chemotherapy for acute lymphoblastic leukemia with testicular relapse. He presented with recurrent dysuria and gross hematuria. Cystoscopy revealed a 2-centimeter irregular sessile mass at the bladder base adjacent to left ureteral orifice. Transurethral resection of the tumor was performed. The histopathological diagnosis was alveolar soft part sarcoma. Chest and abdominal computed tomography showed no evidence of metastasis. He was treated with partial cystectomy and left ureteral reimplantation with negative surgical margin. No evidence of recurrence was found during a 28-month follow-up period with surveillance cystoscopy and computed tomography of the chest and abdomen.