Black Tongue: A Rare Presentation of Rhupus Syndrome

Black tongue is a benign condition typically caused by the overgrowth of dead skin cells, resulting in elongated papillae and a hairy appearance. Other factors contributing to this condition include inadequate oral hygiene, a soft diet, and staining from bacteria, food, yeast, and other substances. It may cause symptoms such as bad breath, a metallic taste in the mouth, and an unsightly black hairy-looking tongue. Here, we present a case of a 30-year-old female who came to our hospital complaining of bad breath and a black tongue for the past month. She had previously taken antibiotics at the primary care medical center, but there was no improvement. We then prescribed her fluconazole, an antifungal medication, for the next two weeks. After two weeks, she returned with a slightly improved tongue color. Further investigation revealed a history of abortion and mild intermittent joint pains, for which she had been self-medicating with over-the-counter acetaminophen. A complete work-up led to the discovery of positive anti-cyclic citrullinated peptide (anti-CCP) antibodies, anti-double-stranded (anti-DS) DNA antibodies, and ANA, leading to the diagnosis of Rhupus Syndrome, an overlap of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).