"Tin Tack" Sign in Localized Cutaneous Leishmaniasis: A Finding from a Nonendemic Disease Focus.

Sir,

Cutaneous leishmaniasis (CL) is a parasitic disease caused by the intracellular protozoan Leishmania and transmitted by the bite of an infected sand fly belonging to the genus Phlebotomus or Lutzomyia. There are estimated 12 million cases worldwide, with 1.5 million new cases being reported annually. In India, the disease has been reported from the hot and dry areas of Rajasthan and Gujarat, with indigenous cases being reported from Kerala, Assam, Haryana, and now recently from Himachal Pradesh, where it is mainly caused by Leishmania tropica.[12] There has been an upsurge in the incidence of CL in this part of the country over the past few years. Most of our patients hailed from two districts of the valley – Kupwara and Baramulla, all located along the northwestern frontier of Kashmir valley and with Kupwara sharing its border with Pakistan-administered Kashmir. Unlike the rest of the valley which is known for cool temperature during summers rarely exceeding 35°C, these areas possess the distinction of having warmer and dry climate. All the affected patients came from low socioeconomic strata, dwelling in mud houses with no proper protection from insect exposure. Moreover, predominant outdoor occupations such as animal rearing and farming accounted for the exposed fraction of population to high risk of the disease.

Lesions mainly occur on the exposed parts, and noduloulcerative type is the predominant clinical type observed in our patients though other atypical forms are also being encountered.

One noteworthy feature observed in our preliminary study was a positive “tin tack” sign which could be elicited in four of our patients in the lesions over face, after obtaining an informed consent from them. The lesions showed a remarkable morphology and evolution from slow growing, painless papules that enlarged to form erythematous, infiltrated plaques with overlying adherent scale and crust.

These patients ranged in age from 16 to 52 years. Two were females and two males. The lesions of CL were localized to the face. Two patients had a solitary plaque over nose; two had similar lesion over chin. Average duration of lesions varied from 6 to 8 months and lesional size ranged from 1 to 6 cm. A closer look at the lesions revealed the appearance of small horny plugs attached to the under surface of the scale removed from the affected site, resembling “tin tacks” or “carpet tacks” penetrating the underlying skin [Figures 1 and 2]. Diagnosis of the disease was made clinically as well by tissue smears and histopathology. Slit-skins smear for Leishman-Donovan (LD) bodies was positive in all four patients. Histopathology showed hyperkeratosis, dilated follicular plugs, epithelioid cell granuloma interspersed with occasional giant cells. LD bodies could be demonstrated in four patients in tissue smears [Figure 3a and b]. However, due to unavailability of modern diagnostic furnishings such as polymerase chain reaction, species identification was not possible in our setup.

Figure 1

Erythematous, infiltrated crusted plaque of cutaneous leishmaniasis with horny plugs on the undersurface involving chin – the “tin tack” sign

Figure 2

Localized cutaneous leishmaniasis on the nose of an elderly male demonstrating the “tin tack” sign

Figure 3

(a) Hyperkeratosis, dilated infundibula with follicular plugging, increased perivascular and periadnexal chronic inflammatory infiltrate (H and E, ×4). (b) Parasitized histiocytes amastigotes of Leishmania. H and E under oil immersion (×100)

All the four patients were treated with sodium stibogluconate, injected intralesionally till blanching of lesion; an alternate day schedule for 3 days in a week in the outpatient clinic which produced consistently reliable response in all patients and no major side effects was noted. Although a positive “tin tack” sign has been a well-portrayed feature of discoid lupus erythematosus (DLE) and has also been reported in localized pemphigus foliaceus,[3] seborrheic dermatitis,[4] postirradiation scalp scales,[5] cutaneous B-cell lymphoma,[6] and lichen planus associated with captopril.[7] Our preliminary study highlights the presence of this sign in a significant number of patients in CL, which to the best of our knowledge has not been reported in the literature previously. Thus, a positive tin tack sign should not be considered exclusively as a feature of DLE but can be seen in other disorders also. Moreover, being a nonendemic area, unearthing the “tic tack” sign in CL from Kashmir valley, assumes all the more epidemiological importance.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.