What should you know about hemosiderotic dermatofibroma?

A dermatofibroma is a compact collection of fibrous and skin-supporting cells. The hemosiderotic pattern contains hemosiderin, a pigment made when blood is broken down in tissue, so the nodule can look darker, rust-coloured, red-brown, or blue-brown. It may feel firm and sit within the skin rather than move freely underneath it. A small inward dimple can appear when the surrounding skin is gently pinched.

Appearance alone cannot reliably distinguish every pigmented skin lump. A clinician may use a dermatoscope and consider the history, surface, borders, colour, and growth pattern. If the diagnosis is uncertain, a skin sample can provide a clearer answer.

Do not pick, cut, or repeatedly traumatise the nodule. Photograph it in consistent lighting and note changes in size, colour, surface, tenderness, or bleeding. Book a skin examination if it is new, difficult to identify, or different from your other marks. If the diagnosis is clear and it causes no trouble, observation may be reasonable. Surgical Excision can be discussed when the lesion is irritating, repeatedly injured, diagnostically uncertain, or cosmetically bothersome.

Arrange prompt review if the lump grows, develops several colours, bleeds without clear injury, forms a persistent sore, becomes increasingly painful, or changes at its edge. Seek earlier assessment when a new pigmented lump appears after a period of stable skin. These changes do not prove cancer, but they do make direct examination more important.

Ask whether the examination is typical of a dermatofibroma, whether dermoscopy or a biopsy is needed, and what change should trigger reassessment. If removal is proposed, ask about the expected scar, wound care, pathology review, and alternatives to excision.