Airway Aspergillosis in Immunocompetent Patient with Thyroid Schwannoma
Invasive Pulmonary Aspergillosis in an Immunocompetent Individual: A Diagnostic Challenge
Table of Contents
Invasive pulmonary aspergillosis (IPA) typically strikes individuals with weakened immune systems. However, a recent case highlights that IPA can also occur in those with healthy immune systems, presenting unique challenges for diagnosis. This case underscores the significance of environmental exposure as a potential risk factor for IPA, even when classic immunosuppressive conditions are absent.
Understanding Invasive Pulmonary Aspergillosis (IPA)
IPA is commonly observed in patients whose immune systems are compromised due to factors such as chemotherapy, corticosteroid use, organ transplantation, neutropenia, or advanced HIV infection.
Increasingly, IPA is being recognized in individuals without traditional immunocompromising conditions but with other underlying risk factors. These include chronic lung diseases like chronic obstructive pulmonary disease (COPD), where corticosteroid use can increase susceptibility to IPA.
In the case presented, the patient did not exhibit any of these typical risk factors. Ther was no history of COPD,asthma,diabetes,kidney disease,or corticosteroid use,all of which are commonly linked to IPA.
Diagnostic Process and Findings
The diagnosis of IPA can be complex, particularly in individuals without apparent immune deficiencies. Guidelines emphasize the importance of considering both host factors and clinical criteria in diagnosing aspergillosis.
According to the Infectious Diseases Society of America’s 2016 update, a thorough diagnostic approach is essential. In this particular case, the patient presented with a cough and hemoptysis, but lacked other systemic symptoms, which initially delayed the diagnostic process.
Though,bronchoalveolar lavage (BAL) and galactomannan testing proved crucial in identifying the presence of *Aspergillus*,confirming the diagnosis of IPA. Galactomannan serves as a valuable biomarker for detecting *Aspergillus* infections, and its presence in BAL fluid strongly suggests IPA, especially when combined with histopathological evidence of the fungus.
Clinical, radiographic, and microscopic evidence are all considered in the diagnosis of Aspergillosis in humans. The patient presented with intermittent symptoms, and a CT chest with contrast revealed a pulmonary nodule that had increased in size compared to prior imaging. Microscopic examination of transbronchial and bronchoalveolar specimens revealed acute branching hyphae with fruiting bodies on GMS stain.
Fruiting bodies are an uncommon microscopic finding. If present,they are the hallmark for histopathologic diagnosis of angio-invasive aspergillosis.
Classically, *Aspergillus* hyphae are characterized as acute branching septate hyphae; nevertheless, it can be challenging to distinguish these hyphae from those of other fungi, such as *Pseudallescheriaboydii*, the *Fusarium* Spp., and *Candida* spp. Therefore,confirmation often necessitates a microbiological isolation by culture,which can be challenging to achieve due to *aspergillus’s* widespread nature. In this case,blood cultures were negative,but cultures from BAL were positive for Aspergillosis.
*Aspergilli* fruiting bodies (Conidia) emerge from mycelia in environments with high oxygen tension or because of severe infections. Unfortunatly, histopathological sections hardly reveal them. Some species of *Aspergillus* can be subtyped in situ based on the shape of their fruiting bodies, which consist of a vesicle and one or two layers of phialides that produce conidia. Contrarily, culture confirmation is necessary for precise species diagnosis.
Treatment and Outcome
The patient’s prompt initiation of voriconazole, the first-line antifungal agent for IPA, was appropriate and essential for managing her infection. Voriconazole has been shown to substantially improve outcomes in IPA, especially when initiated early in the disease course.
Despite the unusual presentation in this case, the patient responded well to voriconazole, reflecting the importance of early and appropriate antifungal therapy even in immunocompetent patients.
Incidental Finding: Schwannoma in the Thyroid Bed
Of note, this case was also unique for the incidental finding of schwannoma in the thyroid bed. Although, there are no clear correlation between airway centered aspergillosis and thyroid schwannoma in the available literature, the patient does have the co-occurrence of both findings sence 2019 when she first moved to US from Cambodia. Moreover, she also endorsed an increase in the size of the left sided neck mass which was confirmed through her recent imaging.
Schwannomas are common in the head and neck region but are unusual in thyroid gland. It is uncommon to see schwannomas in the thyroid bed. There are very few cases reported in the English-language literature, with most of those cases mimicking a thyroid nodule.
Conclusion
This case underscores the need for clinicians to maintain a high index of suspicion for IPA, even in patients who are not traditionally considered at risk. Environmental exposure, particularly in patients with preexisting lung conditions or significant spore exposure, should be considered a potential risk factor for invasive fungal infections.
Clinicians should consider IPA in the differential diagnosis of patients presenting with pulmonary symptoms and relevant environmental exposures, regardless of their immune status. A limitation of this study was that, rather of a BAL PCR test for aspergillosis, a BAL galactomannan test was performed to evaluate the underlying diagnosis.
Invasive Pulmonary Aspergillosis (IPA): Q&A on Diagnosis and Treatment
Invasive Pulmonary Aspergillosis (IPA) is a serious fungal infection,typically affecting individuals with compromised immune systems. However, recent cases highlight its occurrence in immunocompetent individuals, posing diagnostic challenges. This Q&A explores IPA, its diagnosis, treatment, and key considerations for clinicians.
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