Differential Diagnosis for Sudden Small Dark Spot on Tongue

• Single most likely diagnosis
  • Traumatic oral melanin deposition or blood blisters: This is often due to accidental biting of the tongue, which can cause small, dark spots. The sudden appearance and the nature of the spot make this a highly plausible explanation.
• Other Likely diagnoses
  • Oral melanotic macule: A benign condition characterized by a small, dark spot on the mucous membranes, including the tongue. It's a common finding and usually harmless.
  • Hematoma: Similar to blood blisters, a hematoma could form under the tongue's surface, appearing as a dark spot, especially if there was recent trauma.
  • Oral candidiasis (thrush): While more commonly associated with white patches, some forms of oral candidiasis can present with dark spots or areas, especially if there's associated bleeding or if the candidiasis is mixed with other conditions.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Oral cancer: Although less common, any new, unexplained lesion in the mouth, including the tongue, warrants consideration of oral cancer, especially in individuals with risk factors like tobacco use or a history of radiation therapy.
  • Malignant melanoma: Though rare in the oral cavity, it can present as a dark spot and has a high potential for metastasis if not caught early.
• Rare diagnoses
  • Kaposi's sarcoma: This can present as dark spots in the mouth, including on the tongue, and is more common in immunocompromised individuals, such as those with HIV/AIDS.
  • Peutz-Jeghers syndrome: A genetic disorder that can cause dark blue or brown spots on the skin and mucous membranes, including the tongue, though these are usually present from a younger age.
  • Addison's disease: In rare cases, the oral mucosa can exhibit dark spots or hyperpigmentation due to the hormonal changes associated with this condition.