Ichthyosis is characterized by which of the following?

Ichthyosis is a skin condition primarily characterized by the presence of coarse, dry, scaly patches on the skin. The name "ichthyosis" itself is derived from the Greek word "ichthys," meaning fish, which reflects the fish-like appearance of the skin in affected individuals. The condition results from a defect in the skin’s ability to shed dead skin cells effectively, leading to an accumulation of these cells on the skin's surface, which manifests as thickened scales.

The other options describe different conditions or symptoms that are not characteristic of ichthyosis. For instance, itchy rashes are typically associated with conditions such as eczema or allergic reactions rather than ichthyosis. Blistering lesions might indicate various dermatological disorders, such as pemphigus or herpes simplex, but are not indicative of ichthyosis. Excessive sweating is related more to conditions like hyperhidrosis and does not correspond to the scaling and dryness observed in ichthyosis. Therefore, the correct identification of ichthyosis as involving coarse scales on the skin accurately reflects the defining features of this skin condition.