[Right-sided laptop dermatitis].

History And Clinical Findings: A 44-year-old man presented at a dermatologist with a 2 months history of a blue-brown reticular macule on the right thigh that had appeared spontaneously. It was neither painful nor itching and showed no growth or further colour change.

Investigations: Punch biopsy, antinuclear antibodies, CrP, immune electrophoresis, hepatitis serology, urine diagnostics showed normal results.

Diagnosis: On specific inquiry the patient, a long-distance truck driver, reported to rest his laptop during driving breaks always on the right thigh. We diagnosed a "laptop dermatitis".

Conclusion: Consider external mechanical or thermal triggers if skin changes are unilateral. Thermal isolation from permanent heat exposure prevents an erythema ab igne reliably.