Pathology: tenosynovial giant cell tumour

Circumscribed; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells

Occasional collagen bands

Circumscribed; sheets of polygonal cells

Abundant pale amphophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of siderophages; haemosiderin deposition

Occasional collagen bands

Circumscribed; sheets of polygonal cells

Abundant pale amphophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; sheets of siderophages; haemosiderin deposition

Occasional collagen bands

Circumscribed; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of foamy macrophages, siderophages, and haemosiderin deposition

Occasional collagen bands

Circumscribed; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells

Occasional collagen bands

Infiltrative; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of foamy macrophages, siderophages, and haemosiderin deposition

Occasional collagen bands

Infiltrative; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of foamy macrophages, siderophages, and haemosiderin deposition

Occasional collagen bands

Infiltrative; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of foamy macrophages, siderophages, and haemosiderin deposition

Occasional collagen bands

Infiltrative; sheets of polygonal cells

Abundant pale eosinophilic cytoplasm

Monomorphic round-reniform nuclei with small nucleoli; inconspicuous mitotic activity

Irregularly interspersed osteoclast-like giant cells; aggregates of foamy macrophages, siderophages, and haemosiderin deposition

Cleft-like synovial-lined spaces