Tuberculosis of the thyroid in Togo: a clinicopathologic study of 11 presumed cases

Abstract

Tuberculosis (TB) remains a real public health concern in Africa; thyroid localisation of the disease is a very rare form of extrapulmonary TB. We conducted a descriptive and cross-sectional study on all histologically proved cases of thyroid TB diagnosed in Togo over the last 20 years. Eleven cases of TB of the thyroid were identified, of which nine were in women, with an average age of 29.4 ± 0.2 years. The clinical signs were the presence of a nodule in seven, an abscess in three and a swelling with cutaneous fistulisation in one. Thyroid involvement alone was found in four, associated with pleuropulmonary TB in six and mammary TB in one. Human immunodeficiency virus (HIV) co-infection was present in six. All histopathology results showed inflammatory granulomata with caseous necrosis. The clinical features are often misleading and pose a real diagnostic problem, especially with differentials of simple abscess and cancer.

Keywords

Tuberculosis thyroid granuloma caseous necrosis Togo

Background

Tuberculosis (TB) is of significant public health concern globally, with the largest number of diseases documented in sub-Saharan Africa.¹ The World Health Organization (WHO) estimated that there were c. 8.7 million TB cases worldwide with c. 1.45 million deaths attributed to it in 2011.² All viscera may be involved,³ but the thyroid gland is a very rare localisation of TB, being reported in c. 0.1% of cases.⁴ Thyroid TB is difficult to diagnose clinically and is often confused with carcinoma, suppurative abscess or haemorrhage into a thyroid cyst.^4,5 Only a histopathological and/or bacteriological examination can positively confirm the diagnosis. Our paper describes the sociodemographic and histological aspects of thyroid TB observed in Togo.

Methods

We conducted a cross-sectional study using data and histopathological records of the anatomical pathology department at the teaching hospital of Lome. Patients were enrolled between 1996 and 2017. A census in Togo in 2018 estimated its population at 7,440,000. All thyroid TB cases confirmed by histopathological stains with haematoxylin and eosin were included. Parameters noted were age, sex, occupation, HIV positivity, circumstances of discovery and signs including lesion description, and laboratory diagnosis. Extra-thyroid TB locations were also assessed.

This study received approval from the head of the laboratory department to be conducted (Ref no. 08/2017/LAP/CHUSO). Since it was a retrospective study, patient consent was not required. However, during data collection, patient names were not recorded in order to preserve confidentiality.

Results

Eleven cases of thyroid TB were diagnosed: nine were women. During the same period, 823 cases of extrapulmonary TB were diagnosed. Thus, the proportion compared with thyroid TB was calculated at 1.3%. The mean age of the patients was 29.4 ± 0.2 years (range = 14–52). Seven patients had a history of treated TB in lymph node (n = 4) and pleural (n = 3) locations. Tuberculous contact was recorded in one patient. Tuberculin intradermal reaction was positive (≥10 mm) in seven cases with phlyctenular in one further case. Eight cases were immunosuppressed: HIV positivity in six and diabetes in a further two. Six patients were small-scale farmers and five were unemployed (Table 1).

Table 1.

Epidemiological characteristics of patients (n = 11).

Characteristics	Values
Sex
Women	9
Men	2
Age (years)
Average	29.4 ± 0.2
Range	14–52
Profession
Farmers	6
Unemployed	5
Immunosuppressive factor (8/11)
VIH	6/8
Diabetic	2/8
Antecedent of TB (7/11)
Ganglion	4/7
Pleural	3/7

Histopathology

Dominant symptoms found were fever (n = 6), weight loss (n = 4) and neck pain (n = 1). There was a nodule in seven cases, an abscess in three cases and a swelling with cutaneous fistulisation in one case (Table 2). Simultaneous TB was found in seven patients: in the thorax (n = 6) and breast (n = 1).

Table 2.

Main clinical signs of thyroid tuberculosis in Togo.

Characteristics	Values
Circumstances of discovery
Fever	6/11
Weight loss	4/11
Neck pain	1/11
Clinical signs
Nodule	7/11
Abscess	3/11
Cutaneous fistulisation	1/11

Needle puncture in five patients revealed a yellowish fluid, with an average albumin level of 48.2 g/L (range = 13–61 g/L). Caseating material was discovered in three patients. Histopathological analysis revealed inflammatory granulomata of giant Langhan’s and epithelioid cells and lymphocytes surrounding areas of caseating necrosis.

Thyroid ultrasonography performed in four patients demonstrated an abscess in three and a diffuse opacity with fuzzy contours occupying almost the whole thyroid in a patient who had been considered as having a probable malignancy.

Standard anti-TB treatment was administered with favourable results in all patients.

Discussion

Our study has obvious limitations. Patients missed out are those who preferred to seek care from traditional healers, those who consulted other health centres and those who died where no histological samples were available. In addition, ours is a monocentric retrospective study, where direct microscopy and culture for acid-alcohol fast bacilli, and much therapeutic information is missing.

The first case of TB of the thyroid was reported in 1893; since then, there have been few cases of reported TB of the thyroid gland and almost all were associated with tuberculous foci elsewhere in the body.^1,6 TB isolated from the thyroid gland is rare⁶ and found in only 0.6% of TB cases.⁷

The patients in our series were young in precarious socioeconomic circumstances, in agreement with trends reported.^2,3,8 While thyroid TB was previously found only in young women,⁹ HIV infection, affecting men and women equally, is changing this trend.

Biological examinations make little contribution to the diagnosis of thyroid TB,^7,13 but cytological examination may suggest a diagnosis in 73% of cases.⁶ Polymerase chain reaction (PCR) may make this test more sensitive,¹² especially when culture results are negative, or when differentiation from other forms of granulomatous thyroiditis is required.¹³

Histopathological analysis is the kingpin of diagnosis, particularly when thyroid abscess, carcinoma, plasmocyte or idiopathic granulomatous inflammation, actinomycosis, blastomycosis or sarcoidosis are considered.^16–18 Imaging is non-specific and unhelpful. Anti-TB therapy is as effective for other sites of TB.¹⁷

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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