Familial Hypercholesterolemia Mimicking Rheumatoid Arthritis: A Rare Case From Pakistan.

Familial hypercholesterolemia (FH) is a genetically inherited lipid disorder characterized by markedly elevated levels of low-density lipoprotein cholesterol (LDL-C), leading to premature cardiovascular disease and distinctive cutaneous manifestations such as tendon xanthomas and corneal arcus. We present the case of a young Pakistani woman with extensive yellowish plaques over her chest, hands, feet, and periocular area, alongside progressive deformities of the fingers and toes that clinically resembled rheumatoid arthritis, which developed over the course of four years. Laboratory investigations revealed significantly elevated total and LDL cholesterol, while autoimmune markers including rheumatoid factor (RF) and anti-CCP were negative. Radiographic imaging demonstrated soft tissue swelling, reduced joint spaces, and features of acro-osteolysis in the affected digits, suggestive of xanthomatous infiltration. The diagnosis of FH was established using clinical criteria, including the Simon-Broome criteria, Dutch Lipid Clinic Network (DLCN), and MEDPED scores, in the absence of genetic testing due to limited access. The patient was initiated on high-dose statin therapy with dietary and lifestyle modifications, and parents were offered genetic counselling. Although Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors (PCSK9) therapy was considered, its availability and cost posed significant barriers. This case highlights the critical role of physical findings and diagnostic scoring tools in identifying FH in resource-limited settings and adds to the scarce literature by reporting a rare rheumatoid-like presentation of FH, the first of its kind from Pakistan.