CASE 18273 Published on 24.08.2023
0

A case of Pulmonary Mucormycosis with classic imaging findings

Section

Chest imaging

Case Type

Clinical Cases

Authors

Sandra C M1, Breman Anil Peethambar2

1. PG Resident, Department of Radiology, MES Medical College, Kerala, India

2. Consultant Scientist, Entrinsic Bioscience, Norwood, MA, United States

Connected authors
Patient

60 years, male

Categories
Area of Interest Lung ; Imaging Technique CT, CT-High Resolution
Download as PDF Print Show related cases Notify admin
Clinical History

A 60-year-old male patient arrived complaining of worsening fever, breathlessness and non-productive cough for the past 1 month. There was no history of weight loss, chills, hemoptysis, diabetes mellitus, steroid use or malignancy. Physical examination revealed bilateral scattered crepitation. His fasting blood sugar was found to be 286 mg/dl.

Imaging Findings

Computed tomography (CT) revealed 3 nodules with irregular margins noted in the lateral segment of right middle lobe, superior segment of right lower lobe and superior lingular segment of left lower lobe. These lesions showed central ground glass shadows with a peripheral rim of consolidation giving the appearance of a reverse halo sign (RHS) (Figure 1). All lesions showed secondary cavitation and, irregular, intersecting strands within it, giving it the classic appearance of a bird’s nest sign (Figure 3a & 3b).

Another 8.1* 6.2 * 11.9 cm cavity was noted in the superior segment of left lower lobe with thick walls and an air-fluid level within, indicating a lung abscess (Figure 2a & 2b). Following contrast administration, there is very minimal enhancement of the cavity wall seen. The rest of the lesions were non-enhancing. A few enlarged paratracheal lymph nodes were seen within the mediastinum.

Discussion

Pulmonary mucormycosis (PM) is an uncommon, opportunistic angioinvasive infection caused by a fungus belonging to the order Mucorales [1][2]. PM is the second most common manifestation of mucormycosis after rhino-orbital-cerebral infection. Prognosis of PM is poor with mortality approaching 75% [3]. Common risk factors include hematologic malignancies, organ and stem cell transplant, prolonged steroid therapy and diabetes. Symptoms comprise fever, dyspnoea, cough and haemoptysis [4][5].

Radiological features in PM are nonspecific. Lobar and segmental consolidation is the most common imaging finding in a chest radiograph followed by single or multiple nodules and masses which may have a surrounding ground glass halo [6]. The extent of PM is best determined by HRCT. Mark M Hammer et al who reviewed CT studies of 30 patients concluded that nodules were present in 20%, consolidations were present in 57%, RHS in 60%, perilesional halo in 53% and cavitation in 10% of patients [7].

The clinical and radiologic manifestations of PM resemble those of invasive pulmonary aspergillosis (IPA) [8]. However, it is important to distinguish between the two as the treatments involved are different. Various studies have identified a RHS to be associated with PM than with IPA [6] [9-11]. J Vogel conducted a study in which bird’s nest sign could be identified in CT in 22% of patients [12]. Abscess formation was noted in 13% of PM cases in a study conducted by Murphy and Miller [13]. The case presented here showed RHS, bird’s nest sign and abscess formation, all favouring a diagnosis of PM.

Common bacterial infections such as staphylococcus aureus, Klebsiella and mycobacterium, septic emboli, granulomatosis with polyangitis, rheumatoid nodules also present as cavitary pulmonary lesions [14]. Unless surgery is contraindicated, the recommended therapy for PM is early surgical debridement in conjunction with early amphotericin B therapy [15]. Finding of characteristic hyphae in the biopsy specimen remains the gold standard for diagnosis of PM. The patient in this case underwent bronchoscopy and BAL specimen was sent for culture which confirmed the presence of zygomycetes species. The patient was started on injection liposomal Amphotericin B 350 mg in 5 % dextrose over 3 hours following radiological diagnosis.

Teaching points: Imaging findings of PM are nonspecific. However, radiologists should look out for RHS, bird’s nest sign, features of hyphal invasion of arteries along with immunocompromised status of the patient which are more often associated with PM.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Pulmonary mucormycosis
Invasive pulmonary aspergillosis
Pulmonary candidiasis
Granulomatosis with polyangiitis
Septic emboli
Final Diagnosis
Pulmonary mucormycosis
Case information
URL: https://eurorad.org/case/18273
DOI: 10.35100/eurorad/case.18273
ISSN: 1563-4086
License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

Axial non contrast CT image (lung window). Heterogeneous lesion with central ground glass opacity surrounded by consolidation
Axial non contrast CT image (lung window). Heterogeneous lesion with central ground glass opacity surrounded by consolidation forming a complete ring giving a classic reverse halo sign (yellow arrow) in superior segment of right lower lobe.
Figure 2

Axial non contrast CT. (Lung window -2a). (Mediastinal window –2b) 8.1 * 6.2 * 11.9 cm well defined, thick walled cavitary
Axial non contrast CT. (Lung window -2a). (Mediastinal window –2b) 8.1 * 6.2 * 11.9 cm well defined, thick walled cavitary lesion noted in superior segment of left upper lobe with an air fluid level within it indicating abscess formation (red star).
Axial non contrast CT. (Lung window -2a). (Mediastinal window –2b) 8.1 * 6.2 * 11.9 cm well defined, thick walled cavitary
Axial non contrast CT. (Lung window -2a). (Mediastinal window –2b) 8.1 * 6.2 * 11.9 cm well defined, thick walled cavitary lesion noted in superior segment of left upper lobe with an air fluid level within it indicating abscess formation (red star).
Figure 3

Axial non contrast CT (lung window). Cavitary lesions noted in (3a) apicoposterior segment of left upper lobe (blue arrow) an
Axial non contrast CT (lung window). Cavitary lesions noted in (3a) apicoposterior segment of left upper lobe (blue arrow) and, (3b) lateral segment of right middle lobe (green arrow) with irregular and interesting strands within the cavitary lesions with surrounding consolidation giving a bird’s nest appearance.
Axial non contrast CT (lung window). Cavitary lesions noted in (3a) apicoposterior segment of left upper lobe (blue arrow) an
Axial non contrast CT (lung window). Cavitary lesions noted in (3a) apicoposterior segment of left upper lobe (blue arrow) and, (3b) lateral segment of right middle lobe (green arrow) with irregular and interesting strands within the cavitary lesions with surrounding consolidation giving a bird’s nest appearance.