Dear Editor,Castleman's disease (CD) is an enigmatic lymphoproliferative disorder due to its rarity, uncertain aetiopathogenesis and heterogeneous clinicopathologic forms. This case report presents an unusual case of concomitant hyaline-vascular type CD of unicentric retroperitoneal localisation and stage IV (T2N2M0) papillary renal cell carcinoma (RCC). Case ReportA 35-year-old Chinese male was presented with leftsided abdominal pain associated with gross haematuria but with no constitutional symptoms. Physical examination was unremarkable. Full blood count showed haemoglobin 12.0 g/dL, white cells 11,300/μL with normal differential counts, and platelets 803,000/μL. Serum protein was 64 g/L, albumin 32 g/L and calcium 2.31 mmol/L. Hepatic and renal profi les were normal.Computed tomography (CT) urogram revealed a 7.1 cm x 7.7 cm x 8.1 cm mass arising from the left renal upper pole, with enlarged para-aortic nodes. There was also an enhancing nodal mass between the inferior vena cava (IVC) and the portal vein origin, measuring 3.9 cm x 2.4 cm x 4.3 cm with central dystrophic calcifi cation. Staging workup was negative for pulmonary and bony metastases.He underwent an open left radical nephrectomy with renal perihilar lymph node dissection and precaval lymph node dissection. Intraoperative fi ndings were of a 10 cm x 8 cm left renal tumour not involving Gerota's fascia, renal vein and IVC; a 6 cm x 4 cm hard node at the portocaval window adjacent to the pancreatic head extending to the aortocaval space; and a 4 cm x 2 cm perihilar lymph node. Histology showed a papillary type 2 RCC, 7.7 cm in greatest dimension (T2) and Fuhrman nuclear grade 3/4. Three out of 4 perihilar lymph nodes harboured metastatic disease (N2).The gross specimen of the portocaval node consisted of a piece of adipose tissue containing a central hard bony nodule measuring 1.2 cm x 1.1 cm x 1 cm. Microscopically, it exhibited characteristics of hyaline-vascular type CD with calcifi cation and ossifi cation, as well as focal lipophagic reaction (Fig. 1).The patient was later screened negative for human immunodefi ciency virus (HIV). Unfortunately, he relapsed with metastatic disease in his supraclavicular lymph node 19 months after the nephrectomy.

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