Do These Small Subungual Lines Suggest a Larger Problem?

Thin dark lines beneath the fingernails are the only physical findings of note in a middle-aged man who presents with cough, fevers, and arthralgias.

 A 42-year-old man presents with nonproductive cough and subjective fevers and chills with associated arthralgias of 2 weeks’ duration. He admits to a history of intravenous drug use and hepatitis C. He uses daily alcohol and tobacco and currently takes no prescription or over-the-counter medications.

Vitals signs: temperature, 38.3°C (100.9°F); heart rate, 101 beats/min; respiratory rate, 18 breaths/min; blood pressure, 112/72 mm Hg; oxygen saturation, 96% on room air.

His cardiopulmonary examination reveals clear lungs, with a grade II/VI systolic ejection murmur. The rest of his physical exam is unremarkable except for some lesions under the fingernails similar to those shown in the Figure above.

1.  What is this dermatologic manifestation?

2.  What diagnosis might this finding suggest in this patient?

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