Tuberculous placenta: a rare bird but not extinct

tuberculosis, infectious disease/HIV, maternal medicine, chest imaging, neuroradiology, histopathology

A 26-year-old woman from Pakistan presented to our institution in New York with episodic right-sided weakness and expressive aphasia. She was at 36 weeks' gestation of an uncomplicated third pregnancy. On presentation, the patient appeared well, had normal vital signs and was afebrile. Her neurological examination was normal between recurrences. The patient reported usual fetal movement, and fetal monitoring displayed a reassuring tracing. MRI of the brain without gadolinium revealed numerous ring-like hyperintense lesions most consistent with an inflammatory or infectious aetiology (figure 1A). CT of the chest demonstrated multiple bilateral lung nodules with areas of coalescence (figure 1B). The patient denied respiratory symptoms. HIV and vasculitis testing was negative. Interferon gamma release assay had been positive earlier in the pregnancy. Lumbar puncture was performed: there was an elevated opening pressure, lymphocytic pleocytosis, low glucose and high protein. Cerebrospinal fluid smear for acid-fast bacilli (AFB) was negative. Lung biopsy showed non-necrotising granulomatous inflammation with negative AFB stain. Placental tissue obtained at subsequent cesarean section showed diffuse caseating necrosis with giant cells (figure 2). AFB staining was again negative. Empirical anti-tuberculous therapy was initiated and steroids added for meningitis. Eventually respiratory cultures returned positive for sensitive M. tuberculosis, making disseminated tuberculosis (TB) with placental involvement the unifying diagnosis. The neonate was born with APGAR (appearance, pulse, grimace, activity, and respiration) scores of 8/9 and exhibited no evidence of congenital TB. The mother had an uneventful postpartum course.

Figure 1

(A) Axial T2-weighted FLAIR (fluid-attenuated inversion recovery) image from the patient's brain MRI without gadolinium enhancement showing multiple hyperintense subcortical leions with a ring-like appearance (arrows) located in both cerebral hemispheres.(B) Representative axial image from the patient's chest CT without intravenous contrast set to lung windows showing left upper lobe nodules with arrows pointing to the two dominant nodules. The nodule indicated by the lower arrow coalesces with nearby smaller nodules into an area of consolidation.

Figure 2

(A) Low-power view (original magnification ×100) of a section of placental tissue stained with H&E showing near-total obliteration of villous architecture by diffuse caseating necrosis. A few preserved villi can be identified at the periphery of the sample (black arrows). A multinucleated giant cell is present and marked with an asterisk. (B) Higher magnification (original ×400) highlighting the pink-staining necrotic material and the multinucleated giant cell (asterisk) depicted at lower power in (A) (H&E).

The relationship between pregnancy and TB has been the subject of speculation since the Classical period. Whereas pregnancy was considered protective against TB in ancient times, it is now thought to predispose to TB because of the associated immunodeficiency.¹ Obstetrical outcomes are adversely impacted by intrapartum infection. Peculiarities of TB in pregnancy include the frequent absence of typical respiratory symptoms and diagnostic delays due to reluctant imaging. As in non-pregnant patients, lung is the most commonly affected organ by TB in pregnancy, while extrapulmonary disease—of the brain as an example—is very unusual in the HIV-negative adult.² Hematogenous dissemination of M. tuberculosis from the lung is unequivocal when placental tissue is found to be involved. Placental infection is one of the pathways for acquisition of congenital TB by the neonate, which is a major clinical challenge but fortunately quite rare.³ The infected placenta was an organ of great interest to pathologists at the turn of the 20th century as an easily obtainable source of material for the study of TB pathogenesis. The legendary pathologist Aldred Warthin authored several articles on the histopathology of placental TB that provided insight into the response of human tissue to M. tuberculosis.⁴ Careful examination of the placenta has also been known to establish previously unsuspected maternal TB.⁵ In the current case, it eliminated diagnostic uncertainty and triggered empirical therapy for TB, a diagnosis that was later confirmed with respiratory cultures. Although it has received little attention in recent decades, the placenta is not to be overlooked in a pregnant patient with an undiagnosed illness, especially in regions with low TB prevalence and hence low clinical suspicion.

Ethics statements

Patient consent for publication

Not required.

Footnotes

Twitter

Laura Miranda @drlaurapulmcc

Contributors

Conception of manuscript: all authors. Pathology image acquisition and processing: LH. Writing of manuscript: LM, OE. Review and approval of manuscript: all authors.

Funding

The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests

None declared.

Provenance and peer review

Not commissioned; internally peer reviewed.