Keratos follicularis et parafollicularis in cutem penetrans

This code describes Kyrle's disease, a rare acquired perforating dermatosis characterized by the transepidermal elimination of altered keratin and cellular debris. It presents as hyperkeratotic papules or nodules, often with a central plug, typically on the extremities, head, and neck. The condition involves abnormal keratinization and subsequent extrusion of material through the epidermis.

Use this code for patients diagnosed with Kyrle's disease, particularly when the clinical presentation involves the characteristic perforating lesions. Documentation should clearly describe the hyperkeratotic papules or nodules and may include biopsy results confirming transepidermal elimination of keratinous material. This code is appropriate for both primary and secondary forms of the disease.

• Differentiate from other perforating dermatoses like reactive perforating collagenosis or elastosis perforans serpiginosa, which involve different extruded materials.
• Ensure documentation specifies "perforating" to distinguish from non-perforating forms of keratosis.
• Consider any underlying systemic conditions (e.g., chronic renal failure, diabetes mellitus) that may be associated with secondary Kyrle's disease and code them accordingly as co-morbidities.