Palmar spiny keratoderma associated with type IV hyperlipoproteinemia.

We report the case of a 35-year-old man with acquired palmar spiny keratoderma (SK) in association with type IV hyperlipoproteinemia. Cutaneous lesions appeared 11 years before with no history of any previous skin conditions, topical medication or systemic treatment with Vitamin A-derived drugs, x-irradiation, arsenic poisoning or prolonged sun exposure. Family aggregation for SK or other disorders of keratinization was ruled out. Blood chemistries demonstrated hypertriglyceridemia (422 mg/dl) and elevation in plasma concentration of the pre-beta fraction (VLDL) of lipoproteins pattern compatible with a type IV hyperlipoproteinemia. Family aggregation for this metabolic defect was then confirmed. The histologic hallmark of the 'spine' lesion was a compact column of hyperparakeratotic cells (columnar hyperparakeratosis) continuous with a hypogranular layer, without further evidence of dyskeratotic or vacuolated keratinocytes and inflammatory cells in the corresponding dermis. SK represents a well-definite entity which fulfills precise clinico-histologic criteria. However, three main questions are related to SK: differential diagnosis with porokeratosis on histologic examination (columnar hyperparakeratosis or hyperorthokeratosis alone in SK vs. cornoid lamella accompanied by remarkable dermoepidermal changes in porokeratosis); classificative scheme (proper nomenclature to avoid misleading and confounding names); and nosological arrangement (probably two subsets exist: hereditary or benign; and acquired, or idiopathic, which may be paraneoplastic in about 50% of the patients). To the best of our knowledge this is the first case reporting the association between SK and a metabolic impairment although the real connections linking these conditions are still unclear.