Collagenous Fibroma Mimicking a Retrosternal Goiter: A Case Report

A bstrAct Collagenous fibroma, earlier known as desmoplastic fibroblastoma, is a rare fibrous soft tissue tumor that has been described more often in the extremities, where it presents as a slow-growing and painless mass. We report a case of a 48-year-old gentleman, who presented with an anterior neck swelling with substernal extension, resembling a retrosternal goiter, after clinical examination and radiological and cytological assessments. Intraoperatively, we found it to be a mass abutting but separate from the thyroid, arising from the deep aspect of sternum inaccessible from the neck requiring partial-sternotomy for excision. Histopathological examination revealed a hypocellular tumor made of spindle to stellate cells with surrounding stroma showing collagenization with collagen bundles to myxoid changes. This report documents a rare differential for goiter, only the second case reported in the central neck.