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)