A 62-year-old female presents with fatigue and innumerable pruritic, keratotic lesions on her back and neck which she says developed quite suddenly two months ago. A blood test reveals a microcytic anemia with hemoglobin of 9.1 g/dL.
Image credit: @kdh113.
Answer: Gastrointestinal malignancy
These lesions are seborrheic keratoses, and their abrupt onset and pruritic nature are indicative of a possible underlying internal malignancy — a finding known as the sign of Leser-Trélat. In this case, colonoscopy supports a diagnosis of colorectal cancer, one of the most common malignancies associated with this sign. The pathogenesis behind this paraneoplastic syndrome is not well understood, but various growth factors produced by the malignancy may be responsible for the sudden eruption of these lesions. In approximately 50 percent of cases, they resolve with treatment of the underlying malignancy.
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