A 64-year-old male with hypothyroidism was diagnosed with light-chain multiple myeloma in 2003 and underwent multiple external beam radiation therapy sessions, followed by two cycles of vincristine 0.4 mg/adriamycin 18 mg/dexamethasone 40 mg and zoledronic acid 4 mg.
In December 2003, the patient underwent an autologous bone marrow transplant using the Melphalan protocol, which was complicated by graft-versus-host disease, which was managed with multiple lines of antimicrobial agents and corticosteroids.
The patient was kept on regular follow-up until 2011, when he was found to have lytic lesions at the 2nd, 5th, and 6th thoracic vertebrae and cord compression at the tbl6 level, for which he underwent decompression and fixation followed by external beam radiation therapy.
In 2018, the patient was diagnosed with renal failure in Palestine and underwent left forearm antecubital arterio-venous shunt (AVS) procedure to start hemodialysis. Subsequently, the shunt was thrombosed, and another treatment was performed to implant the synthetic AVS (GORE-TEX  Vascular Graft, W. L. Gore & Associates, Inc. Flagstaff, Arizona, USA) on the right forearm. The patient noticed a painless mass around the AVS on the right forearm almost 2 months later. The mass increased in size gradually until it reached 5 cm in diameter but without causing any symptoms other than some technical difficulties in accessing the shunt for hemodialysis. The mass was investigated by ultrasound, and it was reported as a non-vascular mass without any compromise to the venous or shunt systems. Therefore, an open biopsy was scheduled in June 2018.
The pathology was reported as granulation tissue in the form of fibroblasts and necroinflammatory debris. However, the possibility of malignant soft tissue tumor around the AVS could not be ruled out.
The patient was transferred to our orthopedic oncology department in late July of 2018 as a case of a possible tumor in the forearm (Figure. 1). Radiological investigation at our department started by computed tomography (CT) scan with and without contrast of the right forearm, which revealed a recurrent non-enhancing soft tissue lesion at the antecubital fossa, measuring 6 cm in craniocaudal dimension and encasing the AVS without any definite vascular compromise or evidence of associated bony destruction (Figure. 2). Positron emission tomography/CT scan showed multiple hypermetabolic bony and lymphatic lesions, indicating disease progression but without avidity to the forearm mass itself. Magnetic resonance imaging could not be performed due to the lack of material compatibility of the humerus nail, which was inserted outside our hospital for the right humerus fracture of the patient after he fell a few months before presentation.
A multidisciplinary medical decision was made to conduct an excisional biopsy of the mass while trying to salvage the AVS of the patient. The patient and his family were counseled about the procedure and signed consent.
The open biopsy started by a proximal control of the brachial artery and vein, followed by a longitudinal incision over the maximum bulge and with a careful dissection resulting in mass exposure (Figure. 3). Radical en-bloc excision was difficult due to the fragile texture of the mass. Thus, debulking of mass around this synthetic AVS was performed. Adequate hemostasis was attained followed by skin closure in layers. The procedure was followed by internal jugular dialysis catheter insertion as standby dialysis access in case that the AVS was not functioning.
The patient was discharged a few days later, and his first follow-up visit was 2 weeks later when he discovered a recurrence at the same site. The histopathological result came back again as fibro-adipose tissue with scattered multinucleated giant cells and necroinflammatory debris consistent with the atypical presentation of PGS. Thereby, another multidisciplinary clinic decision was made to proceed with radical excision of the mass along with his synthetic AVS.
During the operation, excision of the recurrent tissue was attempted first (Figure. 4). Subsequently, we focused on the AVS removal, retaining less than 1 cm of graft stumps attached to the native vessels where they were closed using Prolene 5-0 suture. Next, an extensile longitudinal incision, connecting both of the previous proximal incisions, was utilized distally, which led to a better exposure. Finally, the abnormal tissues were completely removed until the superficial volar muscles were reached. All of the obtained gross materials along with the removed AVS were sent for permanent pathology, and special care was taken to preserve the important nerves, ensuring adequate hemostasis and closure over a drain.
The patient was discharged on postoperative day 4; he was observed in the clinic almost a month after with no signs of recurrence (Figure. 5). The patient decided to continue his suggested treatment plan in his home country. The final pathology showed the same pathology, which was consistent with the semisolid jelly-like subtype of PGS. During regular virtual follow-up, the patient experienced no recurrence, until he passed away in December 2019 due to myocardial infarction.