Retroperitoneal gossypiboma mimicking renal tumor in a postrenal transplant patient: A diagnostic challenge.

A 68-year-old male had presented with abdominal pain and vomiting of 3 months duration. He had undergone deceased donor renal transplantation 9 years back elsewhere. His general examination was normal. Abdominal examination revealed 15 cm × 15 cm firm palpable mass in the right lumbar region. His renal function tests were normal. Contrast-enhanced computerized tomography (CECT) scan of abdomen revealed encapsulated hypodense retroperitoneal mass lesion with calcification in the right lumbar region [Figure 1a–c]. The mass lesion was arising from the lower pole of the right native kidney with extension posterior to the transplant kidney [Figure 1d]. Subsequently the patient underwent open extraperitoneal exploration in flank position. A 15 cm × 12 cm tensely cystic encapsulated mass was noted between right native and transplant kidney [Figure 2a and b]. The mass was in continuity to the native kidney and densely adherent to psoas sheath. The mass was also adherent to the posterior aspect of the upper pole of the transplanted kidney. The mass along with right native kidney was mobilized all around before reaching the renal hilum. After ligating the renal vein and artery, the mass along with right kidney was removed in toto. Gross pathology revealed surgical sponge inside the tumor mass [Figure 2c]. Histopathology of the native kidney was normal. The patient's postoperative period was uneventful.

Figure 1

(a) Contrast-enhanced computerized tomography of abdomen showing well-encapsulated tumor arising from the lower pole of native right kidney (hollow arrow); (b and c) the mass shows heterogeneous density suggestive of necrosis along with calcification (hollow arrow); (d) the mass was seen extending posterior to the upper pole of transplant graft kidney (hollow arrow)

Figure 2

(a) Well-circumscribed mass lesion attached to the lower pole of the right kidney with dense adhesions all around (arrow); (b and c) well-encapsulated excised specimen with cut section showing the presence of surgical sponge with necrosis

Gossypiboma is defined as a retained surgical sponge.[1] Gossypiboma can remain silent for lifetime by encapsulation. It can migrate externally to the skin or internally into hollow viscus such as rectum, vagina, bladder, or intestine.[2] The body reacts to the retained foreign body either by fibrinous reaction resulting in encapsulation or by exudative reaction leading to extrusion or fistula formation.[3] Plain X-ray can reveal radiopaque marker and ultrasound can suggest echogenic wavy structures in a cystic mass.[4] CECT scan is the gold standard in equivocal cases. It may suggest calcified mass with capsule formation or hypodense mass with peripheral enhancement or even a spongiform configuration with entrapment of small air bubbles.[4] Wavy striped high-density areas with peculiar infoldings may suggest a retained surgical towel.[5] Gossypiboma should be one of the differential diagnoses along with tumor, abscess, hematoma, or pseudocyst in those presenting with mass lesion with past history of surgery. Mostly, renal tumors have enhancement on contrast imaging due to inherent blood supply while gossypiboma will be noted without enhancement. When the retained gauze does not have radiopaque markers, it will be difficult to distinguish it from an abscess or a hematoma. Gossypiboma can be prevented by meticulous count of surgical sponges and by use of sponges with radio-opaque markers.[6] Gossypiboma is always iatrogenic and has important medico-legal implications; hence, every possible steps have to be taken to avoid its occurrence.

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