Chapter 53

It is a generally accepted concept in medicine that the skin can develop signs of internal disease. Therefore, in textbooks of medicine, one finds a chapter describing in detail the major systemic disorders that can be identified by cutaneous signs. The underlying assumption of such a chapter is that the clinician has been able to identify the specific disorder in the patient and needs only to read about it in the textbook. In reality, concise differential diagnoses and the identification of these disorders are actually difficult for the nondermatologist because he or she is not well-versed in the recognition of cutaneous lesions or their spectrum of presentations. Therefore, this chapter covers this particular topic of cutaneous medicine not by discussing individual disorders, but by describing and discussing the various presenting clinical signs and symptoms that indicate the presence of these disorders. Concise differential diagnoses will be generated in which the significant diseases will be briefly discussed and distinguished from the more common disorders that have minimal or no significance for internal diseases. The latter disorders are reviewed in table form and always need to be excluded when considering the former. For a detailed description of individual diseases, the reader should consult a dermatologic text.

(Table 53-1) When an eruption is characterized by elevated lesions, papules (<1 cm), or plaques (>1 cm), in association with scale, it is referred to as a papulosquamous lesion. The most common papulosquamous diseases—psoriasis, tinea, pityriasis rosea, and lichen planus—are primary cutaneous disorders (Chap. 52). When psoriatic lesions are accompanied by arthritis, the possibility of psoriatic arthritis or reactive arthritis (formerly known as Reiter's syndrome) should be considered. A history of oral ulcers, conjunctivitis, uveitis, and/or urethritis points to the latter diagnosis. Lithium, beta blockers, HIV or streptococcal infections, and a rapid taper of systemic glucocorticoids are known to exacerbate psoriasis. Emerging comorbidities in psoriasis include cardiovascular disease and metabolic syndrome.

Table 53-1 Selected Causes of Papulosquamous Skin Lesions

Whenever the diagnosis of pityriasis rosea ...

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