A clinicopathological study of cutaneous tuberculosis at Dibrugarh district, Assam.

BACKGROUND: Cutaneous tuberculosis forms a small subset of extra pulmonary tuberculosis and has a worldwide distribution. AIMS: The present study is an attempt to find out the incidence, clinical spectrum, and histopathological features of cutaneous tuberculosis.
MATERIALS AND METHODS: A total of 42 cases of newly diagnosed patients of cutaneous tuberculosis attending dermatology out patient department over a period of 1 year were included in the study. A detailed clinical examination and investigations including histopathological examination were carried out.
RESULTS: Scrofuloderma was the most common form seen in 50% cases followed by lupus vulgaris in 42.86%, tuberculosis verrucosa cutis in 4.76%, and lichen scrofulosorum in 2.38% cases. The Mantoux test was positive in 83.33% cases. Characteristic tuberculoid granulomas were seen in 72.22% cases of lupus vulgaris, 42.86% cases of scrofuloderma and all cases of tuberculosis verrucosa cutis and lichen scrofulosorum.
CONCLUSION: Cutaneous tuberculosis is still highly prevalent in upper Assam. Early diagnosis and treatment are essential to prevent its complications.

Introduction

Cutaneous tuberculosis is a form of extra pulmonary tuberculosis with varied clinical presentation determined by the route of infection as well as status of cellular immunity of the host. Most of the cases of cutaneous tuberculosis can be diagnosed clinically but some cases really pose diagnostic challenges. Histopathological features are not pathognomonic but play a corroborative role in diagnosis. The present study is a keen effort to find out the incidence, clinical profile, and histopathological features of cutaneous tuberculosis.

Materials and Methods

The patients of newly diagnosed cutaneous tuberculosis attending Dermatology Out-patient Department of a tertiary care hospital over a period of 1 year were included in the study. A detailed history was taken with particular reference to occupation, trauma, bacillus calmette-guerin (BCG) vaccination, and family history of tuberculosis. A thorough general physical, systemic and cutaneous examination was carried out. All cases were subjected to hemogram, hepatic and renal function tests, enzyme linked immuno sorbent assay (ELISA) for human immunodeficiency virus (HIV), and chest X-ray. Sputum smear examination for acid fast bacilli (AFB) and other radiological investigations were done in relevant cases. A skin biopsy and the Mantoux test were performed in all the cases.

Results and Observations

A total of 42 cases of cutaneous tuberculosis were observed in a patient population of 16,864, the incidence of cutaneous tuberculosis being 0.25%. The study comprised of 23 (54.76%) males and 19 (45.24%) females. The age varied from 3 to 65 years, majority of patients, 25 (59.52%) were in their second and third decades of life. Maximum number of patients, 31 (73.8%), were from tea garden laborers’ families.

The most common clinical type of cutaneous tuberculosis was scrofuloderma seen in 21 patients (50%), followed by lupus vulgaris in 18 (42.86%), tuberculosis verrucosa cutis in 2 (4.76%), and lichen scrofulosorum in 1 patient (2.38%) [Figures 1–4]. Most of the patients had single site involvement but 10 (47.6%) scrofuloderma cases had multiple sites of involvement. Head and neck was the most common involved site both in scrofuloderma (13 cases) and lupus vulgaris (7 cases). A family history of tuberculosis was obtained in 16 (38.1%) cases. BCG scar was present in 15 (35.71%) patients which failed to protect from cutaneous tuberculosis. Cutaneous tuberculosis with multiple site of involvement was mostly seen in nonvaccinated patients. Tuberculosis of internal organs was seen in 22 (52.38%) patients of cutaneous tuberculosis, the most common being tubercular lymphadenopathy in 19 (45.24%) cases followed by bone tuberculosis in 3 (7.14%) cases, pulmonary tuberculosis in 2 (4.76%) cases, and tubercular meningitis in 1 case (2.38%). No case was on corticosteroid or anticancer therapy.

Figure 1

Plaque of lupus vulgaris involving left cheek, neck and chest

Figure 4

Lichen scrofulosorum: lichenoid papules on trunk and proximal limbs

Scrofuloderma with multiple sites of involvement

Tuberculosis verrucosa cutis: Warty plaque on root of thumb

All patients were subjected to the Mantoux test. Thirty-five cases (83.33%) showed Mantoux positivity which included 14 (66.67%) cases of scrofuloderma and all patients of lupus vulgaris, tuberculosis verrucosa cutis, and lichen scrofulosorum. The patients of scrofuloderma with the negative Mantoux test had multiple sites of involvement. Acid fast bacilli were observed in exudates of two cases (9.52%) of scrofuloderma. All the patients were negative for HIV.

On histopathological examination epidermal hyperplasia was observed in 10 (55.56%) cases of lupus vulgaris and both cases of tuberculosis verrucosa cutis. Well-defined tuberculoid granulomas [Figure 5] were observed in 9 (42.86%) cases of scrofuloderma, 13 (72.22%) cases of lupus vulgaris, and all cases of tuberculosis verrucosa cutis and lichen scrofulosorum. In other cases, a diffuse infiltrate of epithelioid cells and Langhan's giant cells was seen. Caseation necrosis was found in all cases of scrofuloderma, 2 (11.11%) cases of lupus vulgaris, and 1 case (50%) of tuberculosis verrucosa cutis. Acid fast bacilli were not seen in histopathological examination of any case.

Figure 5

Well defined tuberculoid granulomas with Langhan's giant cells (H and E, 450×)

Discussion

Cutaneous tuberculosis represents 1.5% of all cases of extra pulmonary tuberculosis.[1] It presents with diverse clinical and histopathological features. The incidence of cutaneous tuberculosis has been reported from 0.15% to 0.26% in various studies.[2-5] In our study, incidence was quite high (0.25%). Males outnumbered females in a ratio of 1.2: 1 as in other studies.[245] Most of the patients were in their second and third decades of life, similarly observed in other Indian studies.[45]

The most common type of cutaneous tuberculosis was scrofuloderma (50%) which was also noticed in some studies.[36] However, other studies[45] from India found lupus vulgaris as the most common type. Head and neck as most commonly involved site was also noticed by others authors.[14] The positivity of the Mantoux test has been reported from 68% to 100% in various studies[347] and our study compared well with their findings.

In one study,[3] epidermal hyperplasia was observed in 41.2% cases of lupus vulgaris and all cases of tuberculosis verrucosa cutis. Our study exceeded its incidence in lupus vulgaris. Tuberculoid granulomas in dermis were reported in 70.6% cases of lupus vulgaris, 39.1% cases of scrofuloderma, and all cases of tuberculosis verrucosa cutis[3] which were comparable to our study. Caseation necrosis was reported in 59% sections of lupus vulgaris and 87% sections of scrofuloderma in a study.[3] However, in another study,[6] caseation necrosis was observed in 8.3% cases of lupus vulgaris.

Cutaneous tuberculosis is an important health problem in this part of the country especially in lower socioeconomic group. Parents should be encouraged for routine BCG vaccination as well as proper nutrition of their children. In many occasions, the varied clinical presentation makes the diagnosis of the disease difficult. Clinicopathological correlation is essentially useful in those cases where clinical presentation poses diagnostic difficulties.