Oncocytic carcinoid tumour of the bladder

We report the case of a 77 year old man who underwent an ultrasound scan for lower abdominal pain. He had no significant medical history. The scan identified a small inguinal hernia, explaining his discomfort. A small filling defect in the bladder was also incidentally reported. Urinalysis revealed no abnormality. A rigid cystoscopy was performed. This revealed a raised swelling with normal appearance of the overlying mucosa, superior to the midpoint of the interureteric ridge. The lesion was approximately 1 × 1.5 cm in diameter. This was completely resected to muscle and sent for histology.

Histopathological examination revealed a neoplasm composed of large cuboidal and columnar cells, with abundant granular eosinophilic cytoplasm and large nuclei, with occasional macronucleoli (fig 1), which formed tubules, cords, and cribriform areas. The stroma was oedematous and contained lakes of mucin. The tissue stained negatively for prostate specific antigen and cytokeratin 20. Positive staining was seen for cytokeratin 7, synaptophysin (fig 2) and chromogranin. Therefore, the tumour was classified as a carcinoid tumour of the oncocytic variety.

Figure 1.

 Haematoxylin and eosin stain of the neoplastic tissue (original magnification, ×50).

Figure 2.

 Tissue stained positive for synaptophysin (original magnification, ×50).

The patient underwent a subsequent computed tomography scan of his chest and abdomen, and no other tumour sites were found. A 24 hour urine collection for 5-hydroxyindoleacetic acid did not suggest residual tumour.

Oncocytic carcinoid tumours are rare. They are a variant of carcinoid tumour whose appearance has ultrastructural similarities to an oncocytoma and are recognised by their abundant eosinophilic and granular cytoplasm. Oncocytic changes are often seen in the salivary and thyroid glands; they are thought to be of a degenerative nature. It has been suggested that the change within a carcinoid tumour may result from local environmental changes, possibly ischaemia.¹ Previous reports of these tumours have been in the lung,² nasopharynx, thymus, and in one report, the kidney.³ The tumours are malignant and capable of metastatic spread. They can also result in a carcinoid syndrome, so that full resection is recommended.

This case is worthy of note in view of its rarity. Carcinoid tumours of the bladder have been reported sporadically, but this is the first report of an oncocytic type. The appearance of the tumour was somewhat innocuous, but early excision biopsy averted potentially more serious consequences later on.