SHM Converge Scientific Abstract ePoster Gallery-A Mass That Was Not Cancer: Thoracopulmonary Actinomycosis Mimicking Metastatic Progression in a Patient With Hypopharyngeal Carcinoma

A Mass That Was Not Cancer: Thoracopulmonary Actinomycosis Mimicking Metastatic Progression in a Patient With Hypopharyngeal Carcinoma

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This case describes a 54-year-old man with newly diagnosed hypopharyngeal squamous cell carcinoma, status post tracheostomy and gastrostomy, who developed two weeks of worsening cough, brown tracheal secretions, progressive dyspnea, cachexia, hypotension, tachycardia, and a tender enlarging erythematous lesion on the left lower chest wall.  

CT chest showed a 5 × 5 × 3 cm pleural-based left lower lobe mass-like lesion with internal hypodensities, traversing vessels, and surrounding ground-glass opacities, raising concern for either metastatic cancer or necrotizing infection. Broad-spectrum antibiotics were started, but the chest wall lesion progressed into a fluctuant abscess and was drained. Culture from the abscess grew <em>Actinomyces radingae</em> after one week of incubation. Further staging showed no distant metastases. The patient improved after targeted antimicrobial therapy.  

The final diagnosis was thoracopulmonary actinomycosis with chest wall extension, mimicking metastatic progression of cancer. This case highlights that actinomycosis is a rare, indolent infection that can closely resemble malignancy on imaging, especially in patients with head and neck cancer, airway instrumentation, or poor nutritional status. Because <em>Actinomyces</em> species are slow-growing and may be missed after prior antibiotic exposure, diagnosis often requires tissue sampling and prolonged culture incubation.  

The key lesson is to maintain a high index of suspicion when imaging suggests both infection and malignancy, since early tissue diagnosis can prevent misclassification of a treatable infection as cancer progression and allow timely antimicrobial treatment.

Asset Subtitle

Eugene J. Kim

Meta Tag

Author List Brian Smighelschi, Charmi Patel, Dhir Gala, Eugene J. Kim, Nisha Palla, Tanzila Salim

Category Clinical Vignettes

Concept Thoracopulmonary Actinomycosis

Concept Actinomycosis

Concept Tissue Sampling

Concept Imaging Mimicry

Concept Malignancy

Distinguished Non-Finalist

Presenter Organization Rutgers New Jersey Medical School

Presenting Author Eugene J. Kim

Track Adult

Keywords

thoracopulmonary actinomycosis

Actinomyces radingae

hypopharyngeal squamous cell carcinoma

chest wall abscess

pleural-based lung lesion

necrotizing infection

metastatic mimic

tracheostomy

tissue sampling

prolonged culture incubation

Thoracopulmonary Actinomycosis

Actinomycosis

Tissue Sampling

Imaging Mimicry

Malignancy