A patient's tongue shows the pigmented appearance seen in the image. Which of the following could be included in the differential diagnosis EXCEPT (i.e., which one is LEAST likely)?

Correct answer: C. Glossitis

• A. Peutz-Jeghers syndrome produces mucocutaneous melanin macules on the lips, buccal mucosa, and sometimes tongue, associated with intestinal hamartomatous polyps.
• B. Addison disease (primary adrenal insufficiency) causes diffuse hyperpigmentation of oral mucosa (including tongue) due to elevated ACTH stimulating melanocytes.
• C. CORRECT (this is what you would NOT include) — Glossitis refers to inflammation of the tongue (erythematous, atrophic, or 'bald' tongue) — not to discrete pigmented macules or spots. A pigmented tongue lesion is not glossitis.
• D. Physiologic (racial) pigmentation is common in patients with darker skin and can produce pigmented areas on tongue and other oral mucosa.