[Thermographic examination of cutaneous melanocytic nevi]

Abstract

Study objectives: Comparative examination with dermoscopy, thermography, and histopathology of cutaneous melanocytic nevi.

Material and methods: The study was done in 245 patients with 735 melanocytic nevi and in 12 patients with malignant melanoma. All melanocytic lesions were studied with Heine delta 10 dermatoscope and the total dermatoscopy score (TDS) was calculated. ThermaCAM S.C.500 thermographic camera was used to measure the maximal (Tmax), minimal (Tmin), and average temperatures and to calculate the difference between maximal and minimal temperatures deltaT (degrees C) = Tmax - Tmin for all lesions. Histopathology was performed in the case of 127 melanocytic nevi and 12 malignant melanomas. Statistical analysis was done using Statistica 6.0 software. Mean values in the groups were compared with Student's t-test and Pearson's linear correlation coefficient (r) was calculated to disclose relationships between variables.

Results: TDS was 4.03 +/- 0.68 for all 735 melanocytic nevi, 3.89 +/- 0.30 for 554 ordinary melanocytic nevi, 5.19 +/- 0.21 for 181 atypical melanocytic nevi, and 5.96 +/- 0.25 for 12 malignant melanomas. Mean maximal temperature for all 735 melanocytic nevi was 33.5 +/- 0.3 degrees C and did not differ significantly from the control group (33.2 +/- 0.6 degrees C; p > 0.05). Mean maximal temperature was 33.1 +/- 0.7 degrees C (p > 0.05) for 554 benign melanocytic nevi, 33.7 +/- 0.4 degrees C (p < 0.05) for 181 atypical melanocytic nevi, and 34.1 degrees 0.8 degrees C (p < 0.01) for 12 malignant melanomas. Mean average temperature for all 735 melanocytic nevi was 31.9 +/- 1.0 degrees C and did not differ significantly from the control group (31.8 +/- 0.9 dgrees C; p > 0.05). Mean average temperature was 31.8 +/- 1.0 degrees C (p > 0.05) for 554 benign melanocytic nevi, 32.0 +/- 1.1 degrees C (p > 0.05) for 181 atypical melanocytic nevi, and 33.0 +/- 0.9 degrees C (p < 0.01) for 12 malignant melanomas. Mean deltaT (degrees C) for all melanocytic nevi was 1.2 +/- 0.2 and did not differ significantly from the control group (1.1 +/- 0.2; p > 0.05). Mean deltaT (degrees C) was 1.1 +/- 0.3 (p > 0.05) for 554 benign melanocytic nevi, 1.39 +/- 0.28 (p < 0.001) for 181 atypical melanocytic nevi, and 1.6 +/- 0.4 (p < 0.001) for 12 malignant melanomas. Positive correlations were found between the results of dermoscopic, thermographic, and histopathologic examination of melanocytic nevi.

Conclusions: (1) Thermography may supplement dermoscopy during examination of atypical melanocytic nevi and other skin lesions suspected of neoplastic metaplasia. (2) Dermoscopic findings (including TDS) correlate with thermographic findings--including deltaT (degrees C), as well as with histopathologic findings. (3) Melanocytic nevi demonstrating delta (degrees C) > 1.4 and TDS > 4.75 require surgical intervention or follow-up for neoplastic metaplasia. (4) Average temperatures of benign and atypical melanocytic nevi do not differ significantly from the average temperature of the skin without pigmented lesions.