Reticular erythematous mucinosis: Relationship between its dermoscopic and histopathological findings

Key Clinical Message In reticular erythematous mucinosis, (1) the presence of dotted vessels and (2) uniform, structureless, yellowish‐white spots, and patches on dermoscopy correspond to histopathological findings of (1) vessels at the tips of the dermal papillae and (2) thickening and rupture of the collagen and fiber bundles with mucin deposition, respectively. Abstract Reticular erythematous mucinosis is a rare form of skin mucinosis that primarily affects middle‐aged women, typically appearing as papules and plaques in the upper chest or midline of the back. Here, we report the case of a 75‐year‐old woman with skin papules and plaques left untreated for 8 years. A gross skin examination was followed by histopathological and dermoscopic examinations. The main dermoscopic findings were (1) dotted vessels and (2) uniform structureless yellowish‐white spots and patches. The corresponding histopathological findings were (1) vessels at the tips of the dermal papillae and (2) thickening and rupturing of the collagen and fiber bundles with mucin deposition, respectively. Laboratory investigations revealed normal results, ruling out various autoimmune disorders. REM was diagnosed based on these findings. The study presents relevant evidence‐based findings in dermatology and cutaneous pathology as it is the first description of REM using dermoscopy. Dermoscopic diagnosis without other unnecessary tests would benefit both the clinician and the patient.