We present the case of a 64-year-old man with no history of interest, who consulted for a 17 kg weight loss, asthenia, anorexia and anaemia. Colonoscopy showed non-specific inflammatory changes of the colonic mucosa and gastroscopy showed gastric neoplasia and antral gastropathy, with biopsies taken. Histology of the gastric biopsy confirmed a neoplastic proliferation with a solid pattern suggestive of GIST, and immunohistochemistry was positive for CD117.
Subsequently, he started with oedema in the lower limbs and diarrhoea. Laboratory tests showed: haemoglobin 8.7 g/dl, haematocrit 28%, mean corpuscular volume 75, serum creatinine 1.3 mg/dl; total protein 5.9 g/dl; albumin 1.36 g/dl; cholesterol 96 mg/dl; transferrin saturation index 13%. Proteinuria 5.1 g/day and sediment with 4-6 red blood cells/field. Given the patient's poor condition, renal biopsy was not performed and it was assumed that the amyloidosis previously observed in the gastrointestinal biopsies was responsible for the nephrotic syndrome and diarrhoea. Cardiac amyloidosis was ruled out by echocardiogram.
Treatment was started with a selective cKit tyrosine kinase inhibitor, Imatinib (Glivec®), 100 mg daily. 15 months after diagnosis, surgical excision was decided after a decrease in tumour mass was observed on positron emission tomography/computed tomography. Pathological anatomy confirmed the involvement of the excised stomach and splenic flexure of the colon. As such, it was classified as a high-risk GIST (> 5 cm in size, > 5 mitoses per high magnification field)2.
Renal function continued to deteriorate, so he finally entered a regular haemodialysis programme, one year and seven months after the GIST was found, with the diagnosis of chronic renal failure secondary to AA amyloidosis.