Oral melanotic macule

by Jason Wasserman MD PhD FRCPC
May 10, 2024

An oral melanotic macule is a benign (noncancerous), flat, pigmented spot found on the mucous membranes of the oral cavity. It is not a type of cancer nor a precursor to cancer but is simply a localized area of increased pigmentation.

Does an oral melanotic macule need to be removed?

This lesion is generally harmless and requires no treatment unless there is a cosmetic concern or diagnostic uncertainty about its nature. In such cases, a biopsy may be performed to confirm the diagnosis and rule out other pigmented lesions.

What does an oral melanotic macule look like?

An oral melanotic macule appears as a well-defined, flat patch that can be brown, blue, or gray in color. It is typically small, usually less than 1 cm in diameter, and is most commonly found on the lips, especially the lower lip, but can also appear on the gums, palate, or inner cheeks.

What causes an oral melanotic macule?

The exact cause of oral melanotic macules is not well understood. They may be influenced by factors such as chronic sun exposure, especially those on the lips, or may simply be a focal increase in melanin production for reasons that are not clear. They are not caused by any known infectious or systemic conditions.

Are oral melanotic macules associated with an increased risk of developing cancer?

Oral melanotic macules are benign and are not considered a risk factor for developing cancer. They do not have malignant potential, which means they do not turn into cancer over time.

Microscopic Features

Under microscopic examination, an oral melanotic macule shows an increased amount of melanin in the basal layer of the epithelium and/or the superficial lamina propria. There is usually no increase in the number of melanocytes (the cells that produce melanin), which distinguishes it from other pigmented lesions such as nevi or malignant melanoma. The overlying epithelium is typically normal without any signs of dysplasia or atypical cells. The melanin can be highlighted by a special stain called Fontana-Masson. In contrast, an iron-special stain is usually negative.

About this article

Doctors wrote this article to help you read and understand your pathology report. Contact us if you have any questions about this article or your pathology report. Read this article for a more general introduction to the parts of a typical pathology report.

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