Thoracic Actinomycosis Mimicking Tuberculosis Presenting as Pneumonia and a Chest Wall Mass.
5 affiliations
- 1Medicine, Salford Royal NHS Foundation Trust, Manchester, GBR.
- 2Neurology, Salford Royal Hospital, Manchester, GBR.
- 3Diabetes and Endocrinology, The Christie NHS Foundation Trust, Manchester, GBR.
- 4Emergency Medicine, Darlington Memorial Hospital, Darlington, GBR.
- 5Internal Medicine, Salford Royal NHS Foundation Trust, Manchester, GBR.
Abstract
Thoracic actinomycosis is an uncommon chronic infection caused by Actinomyces species. It can produce pulmonary consolidation and extend across tissue planes into the chest wall, closely mimicking tuberculosis or malignancy. A previously well woman in her 20s presented with 2-3 weeks of left posterolateral chest wall pain, progressive swelling, weight loss of 2-3 kg, cough and haemoptysis. She had had two earlier episodes of left-sided pneumonia treated with short antibiotic courses. Examination showed a large (>10 cm), warm, firm, non-fluctuant swelling over the left posterolateral chest wall. Blood tests showed a marked inflammatory response (white blood cell count (WBC): 16.2 × 10⁹/L, C-reactive protein (CRP): 168-169 mg/L) and microcytic anaemia. CT demonstrated superoposterior left lower lobe consolidation with perifissural nodules, volume loss, reactive lymph nodes and a contiguous chest wall collection. Tuberculosis was considered first. Ultrasound-guided biopsy showed a heterogeneous, septated mass with necrosis. Acid-fast bacillus (AFB) staining, tuberculosis polymerase chain reaction (PCR) and mycobacterial culture at eight weeks were negative. Histology showed granulation tissue and abscess with filamentous Gram-positive aggregates suggestive of Actinomyces. Actinomyces was not isolated in culture. She improved on intravenous co-amoxiclav and completed a prolonged oral β-lactam course, later changed to cefalexin after microbiology review. This case illustrates the difficulty of diagnosing thoracic actinomycosis when it presents with contiguous pulmonary and chest wall disease. Histology supported a presumptive diagnosis. Actinomycosis should be considered when chronic pulmonary infection extends into the chest wall, particularly after tuberculosis has become substantially less likely.
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BibTeX
@article{fayyaz2026thoracic,
title = {{Thoracic Actinomycosis Mimicking Tuberculosis Presenting as Pneumonia and a Chest Wall Mass.}},
author = {Mohsin Fayyaz and M A Sayed Joy and Manasi Limaye and Shaheryar Khan and Muhammad Ali},
journal = {Cureus},
year = {2026},
month = sep,
doi = {10.7759/cureus.117069},
url = {https://europepmc.org/article/MED/42953265},
note = {CC BY},
}
RIS
TY - JOUR
TI - Thoracic Actinomycosis Mimicking Tuberculosis Presenting as Pneumonia and a Chest Wall Mass.
AU - Mohsin Fayyaz
AU - M A Sayed Joy
AU - Manasi Limaye
AU - Shaheryar Khan
AU - Muhammad Ali
PY - 2026
DA - 2026/09/28
JO - Cureus
DO - 10.7759/cureus.117069
UR - https://europepmc.org/article/MED/42953265
AB - Thoracic actinomycosis is an uncommon chronic infection caused by Actinomyces species. It can produce pulmonary consolidation and extend across tissue planes into the chest wall, closely mimicking tuberculosis or malignancy. A previously well woman in her 20s presented with 2-3 weeks of left posterolateral chest wall pain, progressive swelling, weight loss of 2-3 kg, cough and haemoptysis. She had had two earlier episodes of left-sided pneumonia treated with short antibiotic courses. Examination showed a large (>10 cm), warm, firm, non-fluctuant swelling over the left posterolateral chest wall. Blood tests showed a marked inflammatory response (white blood cell count (WBC): 16.2 × 10⁹/L, C-reactive protein (CRP): 168-169 mg/L) and microcytic anaemia. CT demonstrated superoposterior left lower lobe consolidation with perifissural nodules, volume loss, reactive lymph nodes and a contiguous chest wall collection. Tuberculosis was considered first. Ultrasound-guided biopsy showed a heterogeneous, septated mass with necrosis. Acid-fast bacillus (AFB) staining, tuberculosis polymerase chain reaction (PCR) and mycobacterial culture at eight weeks were negative. Histology showed granulation tissue and abscess with filamentous Gram-positive aggregates suggestive of Actinomyces. Actinomyces was not isolated in culture. She improved on intravenous co-amoxiclav and completed a prolonged oral β-lactam course, later changed to cefalexin after microbiology review. This case illustrates the difficulty of diagnosing thoracic actinomycosis when it presents with contiguous pulmonary and chest wall disease. Histology supported a presumptive diagnosis. Actinomycosis should be considered when chronic pulmonary infection extends into the chest wall, particularly after tuberculosis has become substantially less likely.
SN - 2168-8184
ER -