Cutaneous manifestations of internal diseases.

One of the best-recognized cutaneous manifestations of internal disease includes the skin changes seen in endocrine diseases. Cutaneous manifestations of internal disease can also be seen with certain neoplastic processes. Metabolic disturbances in zinc, lipid metabolism, or increased amino acid catabolism can result in zinc-responsive dermatosis, cutaneous xanthomas, and superficial necrolytic dermatitis, respectively. Certain infectious diseases can result in skin lesions that may provide visual clues but also critical diagnostic information if the skin is biopsied and cultured. Recognizing those skin changes that are clinical markers for internal disease can expedite the diagnosis and timely management of several systemic diseases.

Dermatopathy in juvenile Angus cattle due to vitamin A deficiency.

In juvenile cattle, vitamin A deficiency is reported most commonly as a neurological condition; only rarely are there dermatologic manifestations. In the current study, alopecia, severe epidermal and follicular orthokeratosis, and acanthosis due to hypovitaminosis A are reported in 2 of 32 Angus calves, with a third animal suspected. Affected animals responded to vitamin A supplementation, and no additional calves displayed signs. Vitamin A acts on skin by regulating DNA transcription in keratinocytes, reducing the number of tonofilaments and desmosomes, both involved in cell-to-cell adhesion. Hence, adequate levels of dietary vitamin A are necessary for normal keratinocyte turnover, and deficiencies result in retention of keratinized cells (orthokeratosis). The present report reminds diagnosticians to consider vitamin A deficiency in cases of orthokeratotic dermatopathy in cattle.