Ichthyosis Hysirix

This form is the more severe and rare manifestation of the disease, and presents a variety of developments. It is characterized by the excessive growth and accumulation of epidermis in the form of thick, irregularly shaped, variously colored, horny masses, which admit of being detached, exposing a dry and rough surface; or by more marked hypertrophied papillary growths which are surmounted by variously sized and shaped horny projections. In some instances they take the semblance of the quills of the porcupine; hence the name, hystrix. Its distribution may extend irregularly over various parts of the body, or may be localized in one or more well-defined patches, as, for instance, about the axillary folds, the knees, elbows, neck, or other regions. This form is also of gradual growth, is the most advanced, and its degree of development increases with age.

The eruption is particularly severe and annoying in winter, and sometimes diminishes in summer, recurring again the succeeding winter.