What is the appropriate duration of a therapeutic trial in cutaneous tuberculosis? Further observations.

BACKGROUND: Laboratory tests for the diagnosis of cutaneous tuberculosis lack adequate sensitivity and specificity and a trial of therapy is often used as a diagnostic test in difficult cases. However, the duration for which the trial should be undertaken is not clearly defined. Our previous study indicated that one month of therapy was adequate to detect a clinical response to treatment. However, about half the patients first reported after one month of treatment, some much later. METHOD: We therefore analysed the treatment records of 107 patients who received four-drug, short course, antitubercular therapy for a diagnosis of cutaneous tuberculosis in our hospital and who were asked to return for follow-up at biweekly intervals in the first month of treatment. RESULT: Twenty-one patients did not return for any follow-up visit, nine patients did not respond to treatment and treatment was stopped in one patient. Of the remaining 76 patients, 72 patients were recorded to have distinct clinical improvement within five weeks of starting treatment while only four patients showed improvement after 60-123 (8-17 weeks) days of therapy. CONCLUSION: These findings indicate that five weeks appears to be an adequate duration of a therapeutic trial in patients suspected to have cutaneous tuberculosis, with the exception of tuberculids and patients showing minimal clinical activity before treatment. Patients who have not responded by this time are unlikely to do so with further treatment and should have their diagnosis reviewed.

Determination of minimal erythemal dose for narrow band-ultraviolet B radiation in north Indian patients: comparison of visual and Dermaspectrometer readings.

BACKGROUND: Minimal erythemal dose (MED) for narrow band-ultraviolet B radiation (NB-UVB) varies with race and skin type. The aim was to estimate the MED for NB-UVB and compare visual readings with those from a Dermaspectrometer in a north Indian patients as the available data is sparse. METHODS: Forty one patients who visited the dermatology outpatient department were recruited for this study. Skin type was grouped as per Fitzpatrick skin type scale. Patients' upper backs were irradiated after applying a novel template with 8 windows of 2 x 2 cm each, with a test dose ladder of 250-1500 mJ/cm2 in a Waldmann (700K) TL-01 chamber. MED and erythema index were read after 24 hours, the latter by using Dermaspectrometer. RESULTS: Forty one patients (10 males, 31 females) with mean age of 30.5 (14-65) years were recruited. 23 patients were of skin type 5, 17 of type 4 and one of skin type 3. The estimated MEDs were 1000 mJ/cm2 in 17, 750 mJ/cm2 in 19, 1100 mJ/cm2 in four and 500 mJ/cm2 in one patient. The median and mode MED was 1000 mJ/cm2.There was an exponential rise in the erythema index with increase in irradiation (17.18-26.25/250-1500 mJ/cm2). Student's t-test applied to detect differences between the visual and Dermaspectrometer readings was found to be statistically not significant. CONCLUSION: The estimated MED for NB-UVB varied from 500 to 1100 mJ/cm2, the median MED being 1000 mJ/cm2. The darker skin types did not have low MED while some patients with lighter skin type displayed lower MED. There was no significant difference in MED determined by visual and Dermaspectrometer readings.