Bullous reaction to a Mantoux test ; a case report and review of the literature

The tuberculin skin test (TST), (Mantoux test), is useful in detecting populations that have been in contact with the tuberculosis bacillus. Live bacteria are not used in the test so there is no chance of developing TB from the test. However, there are few rare reactions from the test. Swelling and redness of the arm, particularly in people who have had tuberculosis (T.B) or been infected previously and in those who have previously had the BCG vaccine, can occur. Anaphylactic reaction, foreign body reaction, regional lymphangitis and adenitis have all been reported.


INTRODUCTION
The tuberculin skin test (TST), (Mantoux test), is useful in detecting populations that have been in contact with the tuberculosis bacillus.Live bacteria are not used in the test so there is no chance of developing TB from the test.However, there are few rare reactions from the test.Swelling and redness of the arm, particularly in people who have had tuberculosis (T.B) or been infected previously and in those who have previously had the BCG vaccine, can occur.Anaphylactic reaction, foreign body reaction, regional lymphangitis and adenitis have all been reported.Likewise bullous lesion from the test is a rare event.
Herein, We report a case that develops a bullous lesion from the test.

CASE REPORT
A 38-years housemaid Filipino female develop a 3 CM blister 1 day after TST (Fig. 1).The patient was tested because, she had progressive enlargement of the left cervical lymph nodes, (Fig. 2), for the last 3 months which were thought to be due to T.B.
The patient reported that she had generalized itching with excoriations all over the body two weeks before

ABSTRACT
The tuberculin skin test is widely used in the diagnosis of latent tuberculosis infection Blistering skin lesion from the test is rarely observed.In this manuscript, I report a patient who develops a bullous lesion from the test and I review the related literature.   the test.Her itchiness was diagnosed by a primary care physician as scabies but she does not know the names of the medications giving to her.
The tuberculin test done for her is 0. General physical and systemic examinations were normal, except for single non-tender lymph nodes approximately 4x2 cm in the left side of the neck.
The generalized tiny skin excoriations were compatible with a healed scabies lesions, although skin scrapping failed to show any mites.
Erythrocyte sedimentation rate was 45 mm in the first hour.But, the hemogram, liver and kidney function tests, blood sugar and urine examination were normal.Venereal Disease Research Laboratory (VDRL) and enzyme linked immunosorbent assay (ELISA) for human immunodeficiency virus (HIV) were nonreactive.Chest radiograph did not show infiltration/ adenopathy and abdominal ultrasound was normal.
A fine needle aspiration cytology of the left cervical lymph node, carried out later, confirmed evidence of granuloma and necrosis along with acid fast bacilli (AFB).She was diagnosed as tubercular lymphadenitis and started on antituberculous medications.
TST is important for the dermatologists because of an increasing incidence of tuberculosis associated with HIV infection, and also because screening is a necessary part of the work-up before use of antitumor necrosis factor biological drugs (for example, in psoriasis) [2].Box 2, summarizes important facts about the test.
A positive test can result from clinical or latent tuberculosis infection, from BCG vaccination or from contact with environmental mycobacteria.
The results of this test must be interpreted carefully.The person's medical risk factors determine the size of induration the result is positive (5mm, 10mm, or 15mm).In Table 1, We listed some of the causes of false positive and false negative results.
Normally, a cut-off of 5mm induration is used to determine those at high risk of tuberculosis infection, for example close contacts of an active case, patients with radiographic abnormalities consistent with tuberculosis, those with HIV infection and those • It is given intradermally, on the left forearm as 0.1 ml and read after 48 to 72 hours • Reading depends on the induration and not the erythema • The induration is measured as (palpable raised, hardened area) across the forearm (perpendicular to the long axis) in millimeters.If there is no induration, the result should be recorded as "0 mm" • The higher the risk a person has for developing active tuberculosis, the smaller the diameter criterion used for defi ning positivity in a tuberculin skin test result • In case a second tuberculin test is necessary it should be carried out in the other arm to avoid hypersensitising the skin • It is not specifi c for TB as PPD is a culture fi ltrate of tubercle bacilli containing over 200 antigens shared with bacille Calmette-Guérin (BCG) and many non-tuberculous mycobacterium • For the reaction to be positive, 2 to 12 weeks need to have passed since the tuberculosis infection • The Mantoux conversion is defi ned as a change (within a two-year period) of Mantoux reactivity whereas reversion is defi ned as the change to a negative Mantoux result following a previous positive result • Giving a second TST after an initial negative TST reaction is called two-step testing.If the test is repeated, a larger reading may be obtained due to the immune response being 'recalled' or 'boosted' by the fi rst test • Boosting is maximal if the second test is placed between one and fi ve weeks after the initial test, and it may continue to be observed for up to two years • United States (US) recommends that tuberculin skin testing is not contraindicated for BCG -vaccinated persons, and prior BCG vaccination should not infl uence the interpretation of the test • TST is not recommended in the following situations: Past Mantoux reactions ≥15 mm, previous TB disease, and Infants under 12 weeks old Reactions from TST are not common [5][6][7][8][9][10][11][12].The formation of vesicles, bullae or necrosis at the test site indicates high degree of tuberculin sensitivity and thus presence of infection with tubercle bacilli.
To avoid severe skin necrosis, a tuberculin skin test should be avoided in patients with a history of severe reaction.
An exaggerated response causing giant reaction to tuberculin has been occasionally described in patients with lepromatous leprosy [11].
The case I reported has a tuberculous lympahadenitis.She developed a large bulla in just one day, which is not typical for the delayed hypersensitivity reaction seen with TST.
It is difficult to explain for sure the cause of this reaction.However, I think that her presumed scabies infestation facilitate this unusual reaction.
Eosinophils which are one of the important elements of type I hypersensitivity reaction are predominate in scabies and could have switched the reaction from Type IV to Type I or to an unusual Type IV reaction.
Scabies by itself is reported to present with bullous lesion [13].
This report may be a reminder to dermatologists to be involved actively in assessing tuberculin testing as they are the most expert physicians, in interpreting various skin changes associated with intradermal testing.

Figure 1 :
Figure 1: Large bullous lesion at the site of tuberculin test.Note that, the tiny excoriations of supposedly scabies lesions are just visible.

Box 1 :Box 2 :
The contents of 0.1 skin test done to the patient Tuberculin purifi ed protein derivative (PPD) (Bioequivalent to 5 IU PPD-S) Some facts about TST

Table 1 :
Causes of false results of PPD