Differential Diagnosis

The patient's presentation of sudden-onset brown malar cheek hyperpigmentation and blue-gray discoloration of the sclerae, ears, and left ankle, with lesions remaining stable, suggests several potential diagnoses. These can be categorized as follows:

• Single most likely diagnosis

  • Ochronosis: This condition is characterized by the accumulation of homogentisic acid in connective tissues, leading to blue-gray pigmentation. The sudden onset and specific distribution of hyperpigmentation, along with the blue-gray discoloration, make ochronosis a strong candidate. However, the typical context of ochronosis is alkaptonuria, a genetic disorder, or long-term use of certain medications like hydroquinone, which might not directly align with the sudden onset described.

• Other Likely diagnoses

  • Argyria: Exposure to silver or silver compounds can lead to argyria, characterized by a blue-gray discoloration of the skin and mucous membranes. The distribution of the discoloration in this patient could be consistent with argyria, especially if there was recent exposure to silver-containing products.
  • Hemosiderin deposition: This could result from chronic hemolysis or bleeding disorders, leading to the deposition of hemosiderin in tissues, which causes a brown or blue-gray discoloration. The stability of the lesions and their distribution might suggest a localized form of hemosiderin deposition.
  • Melasma: Although melasma typically presents with brown hyperpigmentation on sun-exposed areas, the sudden onset and specific mention of blue-gray discoloration in other areas make it less likely but still a consideration for the malar cheek hyperpigmentation.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Malignant melanoma with metastasis: Although the description does not strongly suggest melanoma, any new pigmentation, especially in an elderly individual, warrants consideration of melanoma, given its potential lethality.
  • Systemic amyloidosis: Amyloidosis can cause a variety of skin manifestations, including pigmentation changes. Given its systemic nature and potential for serious complications, it's a diagnosis not to be missed, despite being less likely based on the description.

• Rare diagnoses

  • Erythromelanosis follicularis faciei: A rare condition characterized by erythema, hyperpigmentation, and follicular plugging on the face, which could potentially explain the malar cheek hyperpigmentation but not the other findings.
  • Carotenemia: A harmless condition causing yellow-orange discoloration of the skin due to high levels of carotenoids in the blood, which does not match the description provided but is a rare cause of skin discoloration.

Each of these diagnoses has a different set of implications for patient management and prognosis, highlighting the importance of a thorough diagnostic workup to determine the underlying cause of the patient's symptoms.