Leprosy Mailing List, April 30th, 2009
Ref.: Itching in leprosy
From: Narasimha Rao P.,
This mail is in regard to on going discussion on itching in leprosy. Itching is a not a known symptom of leprosy. However, many itchy conditions can occur as co-dermatosis in leprosy patients.
When leprosy patients are seen in dermatology out patient clinics of developing country like
Below mentioned are few commonly associated dermatological itchy conditions modified in leprosy.
Asteatotic leg eczema: More commonly seen bilaterally in BL or LL patients, more so after treatment with Clofazimine which adds to xerosis of skin. This type eczemas continue to occur many years after patient is made RFT. Occasionally unilateral leg eczemas are seen in area of anaesthetic/ hypoaesthetic skin lesions of BT patients. In these type of eczema, although scaling is profuse, often accompanied by fissuring and secondary infection, itching as a symptom is usually very mild or not reported at all in a patient of leprosy, compared to a non-leprosy patients with similar involvement.
Papular urticaria: Papular skin reaction to insect bites commonly observed in tropics is observed to be less symptomatic in BL-LL leprosy patients. Itching is a not a prominent complaint in these patients compared to non leprosy patients with this condition.
Scabies: Wide spread crusted type of scabies, also known as ‘Norwegian scabies, which is known to occur in mentally challenged, paraplegics, immuno-supressed etc, is also reported in leprosy. Vijaikumar M, Thappa DM. Crusted (Norwegian) scabies in leprosy. Indian J Lepr..2001 Jan-Mar;73(1):55-8. Itching which is the principal feature of scabies is absent in this condition.
Tinea corporis: When tinea corporis lesions co-occur in leprosy patients with type I reactions, they could mimic the patches of type 1 reaction, especially regressing phase of patches when they scale off. However, differentiating feature is the tinea corporis patches are itchy and when in doubt scraping for fungal filaments on KOH mount would help in the diagnosis. I have few photographs of this co- infection and would be happy to forward to those interested to have them. The case of patient presenting with itching on buttock turning out to be type 1 reaction on histopathology, (ref: letter from Nunzi E, Italy, Leprosy Mailing List, dated, April 28th, 2009; Itching as presenting symptom of reversal reaction),could be one such instance, as buttock is a common site for tinea infection and it could be a co-infection in this patient.
In summary, it can be stated that itchy dermatological conditions when associated with leprosy patient can be a) masked (incognito) b) less inflamed and show modified tissue reaction, c) less itchy, or d) have normal clinical features. Hence it is important to consider/rule out associated dermatological conditions as a cause of itching in these patients. Unfortunately , however, it is often difficult to rule out even common skin conditions such as papular urticaria, insect bite reactions, early scabies etc. by laboratory tests.
In my opinion, when patient of leprosy complains of itching, careful search should be made for (missed) underlying dermatological condition. The associated conditions could vary depending on the geographical area/ economic/ social status of the patient. This is necessary because itching is not a known feature of leprosy and there is no accepted scientific or pathological basis for it to be present in either during normal course or during reactions of leprosy.
With best regards,
P. Narasimha Rao