What should you know about melanoma in situ pathology?

A pathologist examines tissue removed during a biopsy. The phrase in situ means the melanoma has not been shown to grow into deeper skin layers in the sampled tissue. The report may describe the site, pattern, margins and whether the specimen is complete. Margins are the edges of the removed tissue; a margin involved by melanoma cells can mean that more tissue needs to be removed. This diagnosis is different from invasive melanoma, which has entered deeper skin and is assessed by measurements such as thickness.

Pathology is interpreted alongside the examination and the biopsy details. A report can therefore lead to a treatment discussion even when the visible spot seems small. Learn more about [Melanoma](/conditions/melanoma/).

Arrange a review with the clinician who took the biopsy or a dermatologist. Ask whether the margins are clear and whether a wider [Surgical Excision](/treatments/surgical-dermatology/excisional-surgery/) is advised. The procedure removes a planned border of nearby skin and sends the tissue for another examination. Keep the biopsy wound clean as directed, and protect the area from sun while it heals. A follow-up plan may include regular skin checks and examination of the scar and nearby skin.

Contact the clinic promptly if the biopsy or excision site becomes increasingly red, hot, swollen, painful, or produces pus, or if bleeding does not settle with firm pressure. Seek urgent help for heavy bleeding, faintness, breathing difficulty, or rapidly spreading facial swelling. Contact your dermatologist sooner if a new or changing pigmented area appears, because a separate lesion needs its own assessment.

Ask: What do the margins show? Do I need further excision? Was the whole lesion present in the specimen? How often should my skin be checked? Should close relatives know about skin surveillance? What wound changes should prompt a call?