A case of primary cutaneous nodular amyloidosis: JAMA
A man in his 60s with diabetes underwent biopsy for an asymptomatic shiny indurated plaque on the right plantar foot, which had been slowly growing for the past year. The patient was then referred to a dermatology specialist for further treatment.

The patient reported no fevers, chills, weight loss, or night sweats. He had long-standing, intermittent dyspnea onexertion, but no baseline shortness of breath, orthopnea, or bilateral lowerextremity edema.

The patient had occasional numbness in both legs in stocking distribution, attributed to diabetic neuropathy. Physical examination revealed a 4.5 cm waxy, nontender, smooth-surfaced, cobblestoned plaque located in the sulcus between the second and fourth toes (Figure, A).

A biopsy specimen obtained by the patient’s podiatrist was sent to the dermatopathology laboratory for review. The biopsy specimen demonstrated large amounts of globular eosinophilic material in the dermis that contrasts sharply with brighter pink collagen bundles and scattered plasma cells. Positive Congo red stain results confirmed the presence of amyloid protein (Figure, B and C).

The patient underwent an extensive evaluation for hematological malignant abnormalities in coordination with hematology/oncology specialists as well as assessment of cardiac and renal involvement. Serum protein electrophoresis results were negative for paraprotein although κ and λ were elevated.

A complete blood cell count with differential, urinalysis, metabolic panel, and liver function test results were normal.

Read more here: https://jamanetwork.com/journals/jamadermatology/article-abstract/2565795