Carcinoid tumour of the kidney

Definition

A rare renal tumour, identical to carcinoid tumours found in the lung and at other anatomical sites. The absence of other masses or the dominance of the renal mass argues for its being the primary tumour.

Epidemiology

This is a tumour of adults with a wide age range. There is no gender preference. There is an association with horseshoe kidney and polycystic renal disease.

Clinical features

Patients may present with pain, haematuria, a mass, anaemia or fever.

Macroscopic appearances

The tumour may be found anywhere within the kidney. The mass is well defined.

Histopathology

The cells form trabeculae and cords. The cells are uniform. The nuclei are oval and have "salt and pepper" chromatin. Nucleoli are inconspicuous. Usually stroma is scant but may consist of densely fibrotic bands. Calcifications of varying size are present in some cases.

Rarely, carcinoid tumours arise from renal teratoma.

Immunohistochemistry

Ultrastructure

Neurosecretory granules are present.

Differential diagnosis

• Metastatic carcinoid tumour

• Small cell carcinoma: shows a high mitotic rate, nuclear moulding and necrosis

• PNET: positive for CD99

• Paraganglioma: cells are nested with S100-positive sustentacular cells

• Neuroblastoma: form Homer-Wright rosettes. The is a neurofibrillary stroma.

Prognosis

Metastases to lymph nodes, liver, bone and lung are common, despite which the prognosis is usually good.

References

1 Hansel DE, Epstein JI, Berbescu E, et al. Renal carcinoid tumor: a clinicopathologic study of 21 cases. Am J Surg Pathol 2007; 31:1539-44

This page last revised 9.2.2008

©SMUHT/PW Bishop