Acute Pulmonary Actinomycosis Induced by Immunotherapy and Chemotherapy Used for SCLC Treatment: A Case Report and Literature Review

Abstract

A 66-year-old male patient diagnosed with small-cell lung cancer received chemotherapy and immunotherapy, resulting in successful tumor control. However, the patient subsequently experienced a fever and rapid progression of the pulmonary cavity. Despite sampling bronchoscopic bronchoalveolar lavage fluid for targeted next-generation sequencing (tNGS), the cause remained unidentified. Adding bronchoalveolar lavage fluid to sense metagenomic next-generation sequencing (mNGS) confirmed the infection caused by actinomycetes. The patient's condition improved after active anti-infection treatment. This case was further analyzed and discussed through a comprehensive literature review, focusing on molecular microbiological diagnosis and treatment processes. The points outlined were as follows: the advancement of molecular microbiology has gradually reduced the challenges associated with diagnosing rare infectious diseases such as pulmonary actinomycosis. Additionally, in immunodeficient individuals, certain infectious diseases with a chronic course may exhibit acute and aggressive characteristics, which is of concern to all colleagues. Currently, tNGS and mNGS are widely employed in clinical settings as practical tools for diagnosing infectious diseases. Notably, these two methods are not substitutes for each other but complement each other.

Keywords: lung cancer; metagenomic next-generation sequencing; pulmonary actinomycosis; targeted next-generation sequencing.

Figure 1

Chest CT imaging. (a and b) On September 20, 2022, the anterior subpleural cavity of the upper lobe of the right lung was observed, with a maximum cross-section of 21 mm×20 mm, and the shadow was exudated by ground glass. (c and d) September 24, 2022, The irregular cavity in the anterior segment of the upper lobe of the right lung was significantly enlarged, and the maximum section of the cavity was about 83 mm×54 mm. Flocculent tissue was observed in the cavity, and large flake consolidation and exudation shadows were observed around and in the posterior segment of the upper lobe of the right lung against the background of emphysema. (e and f) On April 21, 2023, the cavity in the upper lobe of the right lung contracted and decreased, and the consolidation exudation was roughly absorbed.