Pathology: brown tumour

Brown tumour

• Chronic renal failure with secondary hyperparathyroidism

• Spindle-polygonal cells with fascicular-storiform pattern

• Pale amphophilic cytoplasm

• Ovoid nuclei with mild atypia; inconspicuous mitotic activity

• Fibrovascular stroma; interstitial haemorrhage with clustering of osteoclast-type giant cells; haemosiderin and siderophages

Non-neoplastic thus not within the WHO Classification (included here to highlight morphologic overlap with other giant cell-rich tumours)