To recall the causes of a diffuse pigmentation of the skin, one might simply visualize various organs of the body where a cause may originate. The adrenal gland brings to mind Addison disease, the liver suggests hemochromatosis, the thyroid suggests hyperthyroidism, the uterus suggests pregnancy (more likely to cause chloasma), and the ovariessuggest the chloasma of menopause. The liver is also the cause of jaundice (see page 279). The skin itself is the site of melanotic carcinoma, which in occasional cases causes a deeply pigmented skin, and tinea versicolor, which produces a patchy yellow-brown pigmented area over the trunk. Any dermatitis that takes a long time to heal may cause a patchy pigmentation.
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Skin mass |
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Skin pigmentation and other pigmentary changes |
Other causes of patchy pigmentation are the cafĂŠ au lait spots of neurofibromatosis, stasis dermatitis from chronic thrombophlebitis and varicose veins, the pigmentation of the dorsal surfaces of the hands and face in pellagra, carcinoid syndrome, porphyria, and Gaucher disease. Ochronosis produces a bluish black or bluish brown pigment of the sclera, ears, skin, and nails. Vitiligo (idiopathic type) suggests a patchy pigmentation but is really a depigmentation.
Approach to the Diagnosis
The workup for diffuse pigmentation involves ruling out hemochromatosis, hepatobiliary disease, and Addison disease with appropriate tests for these disorders (see Appendix A) and using the expertise of a dermatologist in the cases of patchy pigmentation.
Other Useful Tests
1. Wood's lamp (tinea versicolor)
2. Serum electrolytes (Addison disease)
3. Serum cortisol (Addison disease)
4. Serum iron and iron binding capacity (hemochromatosis)
5. Urine porphyrins and porphobilinogen (porphyria)
6. Urine melanin (melanoma)
7. Urine for homogentisic acid (ochronosis)
8. Free thyroxine (FT4) level (hyperthyroidism)
9. Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels (menopause)
10. Skin biopsy
