Title: Drug-Induced Hyperpigmentation Mimicking Peripheral Arterial Disease: A Diagnostic Conundrum

Author(s): Aekta Gupta, MD; Minahal Naveed, MD; David J Gemmel, PhD; Timothy J Barreiro, DO

Email: Agupta@mercy.com

Introduction: Drug-Induced Hyperpigmentation (DIH) presents a diagnostic challenge, often mimicking other conditions such as Peripheral Arterial Disease (PAD). DIH is responsible for 10-20% of acquired hyperpigmentation cases, arising from various mechanisms, including melanin buildup, drug accumulation, pigment production, and iron deposition from skin blood vessel damage. This case report highlights the importance of recognizing DIH, emphasizing the need for a nuanced understanding of medication-induced skin changes.

Case Report: A 66-year-old male with a medical history including diabetes mellitus, scleroderma, PAD, and substance misuse, who presented unresponsive, exhibiting symptoms of diabetic ketoacidosis and severe lactic acidosis. Notably, his lower extremities showed bilaterally symmetrical violaceous discoloration, initially suggestive of PAD. However, further examination revealed extensive blue- gray pigmentation across various body parts, inconsistent with PAD’s typical presentation. CT angiography showed no significant stenosis. This symmetrical hyperpigmentation, combined with the angiographic findings, prompted consideration of alternative diagnoses. Further investigation revealed that the patient had been on long term Minocycline and hydroxychloroquine therapy for scleroderma for past 8 years. Thus, given the extensive areas of discoloration and negative angiogram the diagnosis of Drug- induced hyperpigmentation was made. Older records revealed that a biopsy done in 2015 which had findings suggestive of drug induced hyperpigmentation.

Discussion: This case illustrates the complexity of diagnosing DIH, particularly in patients with existing vascular conditions. Diagnosis of DIH hinges on a detailed medical assessment, drug history, alignment of pigmentation timing with drug use, histological findings. Management primarily involves discontinuing the offending drug and protective measures against sun exposure. DIH can mimic PAD’s clinical features, but key differences, such as the pattern of pigmentation and the presence of peripheral pulses, aid in differentiation. DIH must be considered in patients with unexplained skin hyperpigmentation, particularly those undergoing long term drug therapy. This case highlights the need to be vigilant about medication side effects and the possibility of DIH mimicking PAD in differential diagnoses