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Amyloidosis cutis dyschromica. DNA repair reduction in the cellular response to UV light
S Moriwaki1, C Nishigori, Y Horiguchi
1Department of Dermatology, Faculty of Medicine, Kyoto University, Japan.
Background:
Amyloidosis cutis dyschromica, a special type of primary cutaneous amyloidosis, is assumed to be a congenital disorder and sun exposure is thought to be the major causal factor. Herein we report a case of this rare disease and DNA repair characteristics of UV damages in the fibroblasts derived from the patient.
Observations:
A 24-year-old Japanese woman showed hyperpigmented and hypopigmented xerotic lesions in sun-exposed skin since she was 10 years old; deposits of amyloid material were detected in the papillary dermis. The fibroblasts were hypersensitive to UV-B, but not so sensitive to UV-C. Unscheduled DNA synthesis of the patient's cells after UV-C exposure was lower than that of normal cells at 3 hours and both reached the same level at 6 hours. After UV-B exposure, unscheduled DNA synthesis of the patient's cells was lower than that of normal cells at least until 6 hours after UV exposure.
Conclusion:
Although the origin of amyloidosis cutis dyschromica is unknown, hypersensitivity to UV-B with possible DNA repair defects is suggested to be the cause of this disease.