A 68-year-old man comes to the office to establish care. He has type 2 diabetes mellitus complicated by chronic kidney disease and peripheral sensory neuropathy. Medical history is notable for hypertension and coronary artery disease. The patient works for an agricultural supply company and spends most of his day walking and standing on the warehouse floor. Vital signs are normal. BMI is 34 kg/m². Examination of the lower extremities shows decreased sensation to monofilament testing below the knees bilaterally, with 2+ pitting edema, varicosities, and extensive discoloration, as shown below. Which of the following is the most likely cause of the discoloration in this patient's skin?

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11ec160b_38c7_75e8_9249_53c367dab079_MD0001_00 This patient has varicose veins and edema in the lower extremities consistent with chronic venous insufficiency. Venous insufficiency is a multifactorial process; contributing factors include obstruction of venous return (eg, pregnancy, obesity), increased orthostatic pressure (eg, prolonged standing), decreased muscular compression (eg, sedentary lifestyle), and damaged venous valves (eg, due to deep vein thrombosis). Over time, patients with venous insufficiency can develop extravasation of fluid, plasma proteins, and red cells, leading to chronic inflammation and stasis dermatitis (SD). SD is characterized by erythema, induration, fibrosis, and deposition of hemosiderin (from breakdown of extravasated RBCs) manifesting as reddish-brown discoloration, as in this patient. Symptoms are typically bilateral and usually worse at or above the ankles. Complications of SD include poor wound healing and ulceration. (Choice A) Deposition of calcium phosphate salts leads to calcific uremic arteriolopathy (calciphylaxis). This usually occurs in patients with end-stage renal disease receiving hemodialysis and presents with extremely painful nodules, plaques, and ulcers. (Choice B) Tinea versicolor is a superficial dermatophyte infection that causes primarily macular, rather than regional, pigment changes. It is typically found on the trunk and upper extremities rather than the ankles. (Choice C) Dermal deposition of glycosaminoglycans is seen in patients with untreated hypothyroidism (ie, myxedema) and Graves disease (ie, thyroid dermopathy). It can manifest as induration and thickening of the skin over the shins. (Choice E) Chronic radiation dermatitis is characterized by focal fibrosis and increased production of melanin. It is usually seen following external beam radiation therapy for cancer, and the findings are typically most notable in the treatment field. Educational objective: Stasis dermatitis is characterized by chronic erythema, fibrosis, and reddish-brown discoloration due to deposition of hemosiderin (from breakdown of extravasated red cells). Symptoms are typically bilateral, and usually worse at or above the ankles. Complications include poor wound healing, weeping, and ulceration. __________ References: Stasis dermatitis: pathophysiology, evaluation, and management. (http://www.ncbi.nlm.nih.gov/pubmed/28063094)

A 68-Year-Old Man Comes to the Office to Establish Care