Rhizopus homothallicus, an emerging pathogen causing cavitary lung lesions.

Introduction:  Rhizopus homothallicus is a new emerging pathogen causing Mucormycosis.Case Presentation: We report a case of pneumonia caused by Rhizopus homothallicus in a 54 year old type 2 diabetic patient. The organism was isolated from bronchoalveolar lavage fluid and preliminary identified by fungal morphology and finally by sequencing of the internal transcribed spacer region.Conclusion: Mucormycosis may be associated with cavitary lung lesions in the backdrop of poorly controlled diabetes or other immunosuppressed states. Pulmonary mucormycosis may have variable clinical and radiological presentations. Therefore, strong clinical suspicion and prompt management can prevent high fatality associated with the disease.

SINGLE CAVITARY LUNG LESION IN A HEALTHY YOUNG MALE

Introduction: Mycobacterium malmoense is a slow-growing, non-tuberculous mycobacterium which primarily causes pulmonary disease. M. malmoense is acquired through environmental exposure to contaminated soil or water in individuals with impaired cell immunity. M. malmoense infection may cause extrapulmonary manifestations including cervical adenitis, tenosynovitis, and disseminated disease. Our literature search revealed extremely few cases reported on M. malmoense causing cavitary lesions. We present a case of a patient with hemoptysis and worsening bilateral lung cavitary lesions where sputum culture isolated M. malmoense. Case presentation: A 58-year-old male with a past medical history of hypertension, 80-pack-year smoking history, polysubstance abuse with methamphetamine, cannabis, benzodiazepines, hepatitis C, COPD, and chronic cavitary lung lesions was admitted to the hospital secondary to hemoptysis. He had an initial episode of hemoptysis approximately one year ago which self-resolved after six days. He was scheduled to receive outpatient bronchoscopy for his chronic cavitary lesions though missed follow-up. Two days before the current admission, the patient had worsening cough and bloody sputum. He denied chest pain, night sweats, weight loss, fever, or chills. Computerized tomography (CT) chest showed a new right lower lobe cavitary nodule measuring 3.4 cm x 2.8 cm and unchanged bilateral apical cavitary lung lesions. Our patient was started on IV piperacillin-tazobactam and vancomycin. He had approximately 150 ml of hemoptysis in 24 hours therefore received inhaled tranexamic acid. Sputum smear was positive for acid fast bacilli. Quantiferon TB and HIV testing were negative. Sputum cultures grew Mycobacterium malmoense. Unfortunately, the patient refused any further treatment. Discussion: Mycobacterium species are seen in patients with underlying lung disease or immunocompromised states. Infection is diagnosed by clinical, radiological, and microbiological workup. Microbiological workup includes two separate sputum samples or via transbronchial biopsy or bronchial wash. The most common radiological finding include thick-walled cavitary lung lesions in the upper lobes and underlying pulmonary fibrosis. This Mycobacterium species has high antimicrobial resistance. As per the current ATS and IDSA guidelines, multidrug treatment with macrolides, ethambutol, and rifamycin for a duration of 12 months is indicated. Conclusion: Non-TB Mycobacterium infrequently causes disease, though in susceptible or immunocompromised individuals, it can cause serious respiratory infections. M. malmoense infection still carries a high mortality risk, so careful and early diagnosis is important to improve outcomes. It is important to recognize patients with non-resolving radiographic imaging as well as atypical and persistent infections that do not improve with standard treatment.

Cavitary lung lesions pose a formidable diagnostic challenge due to their multifaceted etiologies. While tuberculosis and other prevalent pathogens typically dominate discussions, instances of community-acquired Pseudomonas aeruginosa (P. aeruginosa) pneumonia leading to cavitation in immunocompetent individuals remain exceptionally rare. Herein, we present a compelling case of such pneumonia in a 61-year-old man with a past medical history of hypertension and coronary artery disease who presented with cough, chest pain, and subjective fever. Chest imaging revealed cavitary lung lesions, which is atypical for community-acquired pneumonia (CAP). Initial workup excluded common CAP pathogens, following which bronchoscopy with bronchoalveolar lavage (BAL) definitively diagnosed P. aeruginosa, prompting targeted antibiotic therapy. Treatment led to clinical and radiographic improvement. P. aeruginosa rarely causes CAP, especially in immunocompetent patients, and cavitary lesions further complicate diagnosis. This case highlights the importance of considering P. aeruginosa in CAP with unusual features and emphasizes the utility of bronchoscopy with BAL for diagnosis and guiding management.

To demonstrate clinical features and outcomes in patients with cavitary lung lesions and COVID-19 associated pneumonia. A retrospective analysis of electronic medical records of 8261 patients with COVID-19 was performed. We selected 40 patients meeting the inclusion criteria. Sex, age, hospital-stay, lung tissue lesion, comorbidities, treatment, methods of respiratory support, complications and outcomes were evaluated. Cavitary lung lesions were more common in men (67.5%). Age of patients ranged from 28 to 88 (mean 64.9±13.7) years. Hospital-stay in patients with cavitary lung lesions was 9-58 (median 27.5) days. There were 18 complications in 14 (35%) patients. Pneumothorax, isolated pneumomediastinum, pleural empyema, hemoptysis and sigmoid colon perforation were considered as complications of cavitary lung lesions. Nine (22.5%) patients died (5 of them with complications). Three patients died after surgical treatment. Long-term results were analyzed in 8 (25.8%) patients. Patients were followed-up for 3 months after discharge. Shrinkage of lesions occurred after 7-60 (mean 23) days, and complete obliteration of cavities came after 32 (range 14-90) days. Cavitary lung lesions are a rare complication of COVID-19 pneumonia. There was no significant correlation of complications with age, sex, therapy, volume of lung lesions and non-invasive ventilation (NIV). Despite more common fatal outcomes in older patients undergoing NIV, the last one was prescribed exclusively due to disease progression and respiratory failure. Further research on this problem is necessary to identify possible risk factors of cavitary lung lesions.

The present study investigates the diagnostic efficiency of apparent diffusion coefficient (ADC) values in differentiating between malignant and benign cavitary lesions on diffusion-weighted magnetic resonance imaging (DWI). This prospective study included 45 consecutive patients identified with a cavitary lung lesion with a wall thickness of ≥5mm on thoracic computed tomography in our clinic between 2020 and 2022, and who underwent thoracic DWI within 1 week of their original computed tomography. ADC measurements were made on DWI by drawing a region of interest manually from the cavity wall, away from the lung parenchyma in the axial section where the lesion was best demonstrated. The patients were then classified into benign and malignant groups based on the pathology or clinico-radiologic follow-up. The sample included 29 (64.4%) male and 16 (35.6%) female patients, with a mean age of 59.06±17.3 years. Included in the study were 1 patient with 3 and 3 patients with 2 cavitary lesions each, with a total for the sample of 50 cavitary lesions. There were 23 (46%) malignant and 27 (54%) benign cavitary lung lesions. The mean ADC value (×10 -3 mm 2 /s) of the malignant and benign cavitary lesions was 0.977±0.522 (0.511 to 2.872) and 1.383±0.370 (0.930 to 2.213), respectively. The findings were statistically significant using an independent samples t test ( P =0.002). The mean wall thickness of the malignant and benign lesions was 12.47±5.51mm (5 to 25mm) and 10.11±4.65mm (5 to 22mm), respectively. Although malignant cavities had a higher mean wall thickness than benign cavities, the difference was statistically insignificant ( P =0.104). A significant difference was identified between the ADC values measured in DWI of the malignant and benign cavitary lung lesions. DWI, a noninvasive and rapid imaging method, can provide useful information for the differential diagnosis of cavitary lesions and can minimize unnecessary biopsies.

AN UNUSUAL PRESENTATION OF MALIGNANCY

Cavitary lung lesion as sequelae of mild COVID-19 in a patient with HIV.

Pulmonary cystic and cavitary lesions caused by diverse etiologies are commonly encountered in chest imaging. The terms "cyst" and "cavity" are used to describe air-filled regions in the center of a nodule or consolidation of the lung. To date, only radiologic aspects of these lesions have been addressed. The morphologies of pulmonary cystic and cavitary lesions exhibit a broad spectrum, ranging from benign to malignant pulmonary diseases of acquired or congenital origin, including variable infectious diseases. In this review, we summarized the differential diagnosis of pathological entities to provide pathologists and radiologists with an overview of the diseases most commonly associated with pulmonary cystic and cavitary lesions in adults and children. The results showed slightly different patterns in the distribution of the diseases in the two groups. The most common causes of cavitary lesions include malignancy and infection in adults, and congenital malformation in children. Therefore, identification of pathologic entities correlating with the radiologic findings, clinical course, and location of the lesion is important in the evaluation of cystic and cavitary lung lesions in order to avoid unnecessary surgical procedures or delayed treatment.

TO CAVITATE OR NOT TO CAVITATE: ATYPICAL PRESENTATION OF A COMMON PATHOGEN

To the Editor: The species Mycobacterium iranicum was described in 2013 (1) on the basis of 8 clinical strains isolated in various countries (Iran, Italy, Greece, the Netherlands, Sweden, and the United States). Recently, the isolation of M. iranicum from the sputum of a woman also was reported (2). We report the isolation of this newly recognized species from an HIV-positive patient. A scotochromogenic, rapidly growing strain was isolated in 2012 from respiratory specimens of an HIV-positive 44-year-old Iranian man with chronic pulmonary disease. The patient had been found to be HIV seropositive (viral load >1,000 copies/mL, CD4 lymphocyte count 120/µL) in 2004 when he was hospitalized because of fever, weight loss, and oral candidiasis. Treatment with antiretroviral drugs, including stavudine, lamivudine, and nevirapine, was begun. The patient rapidly improved; the fever disappeared, he gained weight, and he was discharged from the hospital. At a 6-month follow-up visit, viral load was 1,000 copies/mL and CD4 lymphocyte count was 420/µL. He continued to receive antiretroviral treatment until 2010 when treatment was discontinued because of its high cost. The man was hospitalized again in 2012 with mild fever, weight loss, chronic chest pain, and nonproductive cough. At that time, the viral load was >100,000 copies/mL, and CD4 count was 5 lymphocytes/µL. Tuberculin skin test results were negative, radiograph of the chest showed no abnormalities, and routine cultures of sputum and blood were negative for common bacteria. Lactate dehydrogenase level (98 U/L [reference <600 U/L]) was within normal limits, whereas liver function was abnormal (alanine aminotransferase level 95 U/L [reference <36 U/L], L-aspartate aminotransferase level 85 U/L [reference <29 U/L], alkaline phosphatase 180 U/L [reference 44–147 U/L], and total bilirubin 1.4 mg/dL [reference 0.3–1mg/dl]). Antiretroviral therapy was resumed, which led to an increase in CD4 cells (205 lymphocytes/µL after 1 month). The examination by microscopy (Ziehl-Neelsen staining) of 3 sputum samples did not reveal acid-fast bacilli; culture for mycobacteria was not done. Oral treatment with tetracycline was started, but the patient’s fever and chest pain remained unchanged. After bronchoscopy, 2 of 3 bronchial lavage (BAL) samples were found to be positive for acid-fast coccobacilli by microscopy, and rapidly growing, deep orange mycobacteria grew in all 3 cultures. Giemsa stain did not show Pneumocystis jirovecii in BAL samples. A standard antituberculosis regimen was undertaken but did not result in substantial improvement. At 1 month follow-up, 1 sputum sample was negative for acid-fast organisms, and 1 BAL specimen was positive by microscopy and in culture. When the isolate was identified as M. iranicum, therapy was replaced with a combination of amikacin and ciprofloxacin for 3 months (standard treatment used in Iran for infections caused by rapidly growing mycobacteria), and the patient improved rapidly. Mycobacteria were neither observed nor grew in culture in a BAL specimen obtained 1 month after the change in therapeutic regimen. Identification of the isolates was initially attempted with biochemical tests, and they were negative for niacin production, nitrate reduction, Tween 80 hydrolysis, and semiquantitative catalase. The tests were positive for urease activity, iron uptake, tellurite reduction, arylsulfatase (3 days after the start of the test), 5% NaCl tolerance, and heat-stable (68°C) catalase. The genetic sequencing of almost-complete (1,450 bp) 16S rRNA gene (3), a 710-bp fragment of the β-subunit of the RNA polymerase gene (4), and the hypervariable region (402 bp) of the 65-kDa heath-shock protein (5) revealed 99.8%, 99.4%, and 100% identity, respectively, with sequences of the type strain found in GenBank and definitively confirmed the identification. The clinical criteria required by the American Thoracic Society and Infectious Disease Society of America (3) to assess the importance of the isolation of a nontuberculous mycobacterium from pulmonary specimens include, in adjunct to a specific symptomatology, the presence of nodular or cavitary lung lesions and the exclusion of any other possible cause of the disease. The normal thoracic radiograph findings for the case-patient described here cannot, however, be considered a definitive exclusion criterion: in highly immunocompromised patients, a chest radiograph may show no abnormalities, even when substantial pathologic features of infection are present (6). The microbiological criteria were clearly fulfilled by isolating the organism from multiple sputum specimens and the BAL specimens. The patient’s response to the treatment and the disappearance of thoracic symptoms further support the assertion. Our report confirms the potential pathogenicity of M. iranicum. In addition to the case described here, 9 isolations of this species have been reported so far. Among them, the clinical relevance has been demonstrated for 2 strains grown from respiratory specimens of patients with pulmonary disease and for 1 strain isolated from a cutaneous lesion (1,2). The role of an accurate identification, in conjunction with symptoms and radiographic findings, is central to understanding the clinical significance of mycobacteria isolated from pathologic specimens.

Objective: To report the risk factors, clinical characteristics and treatment courses of pulmonary mucormycosis after lung transplantation(LT). Methods: We included 3 cases with pulmonary mucormycosis after LT from March 2017 to July 2020 in the centre for lung transplantation of China-Japan Friendship Hospital. Twelve cases from Chinese and English literature from China National Knowledge Infrastructure (CNKI), China Biomedical Literature Service System and Pubmed Database from March 1980 to July 2020 were added. The risk factors, clinical characteristics and treatment courses of all cases were summarized and analyzed. Results: Pulmonary mucormycosis occurred in 1.06% (3/284) in our centre. A total of 15 cases with 12 cases from literature included 10 males and 5 females with a mean age of(47±20)years. Thirteen cases occurred after LT, and 2 cases occurred after heart-lung transplantation (HLT). Nine probable cases were diagnosed by positive isolation of the pathogen from bronchoalveolar lavage fluid or sputum. Three proven cases were diagnosed by transbronchial lung biopsy. Meanwhile, the other 3 proven cases diagnosed by CT-guided percutaneous lung biopsy, autopsy and surgical operation respectively. Ten cases (66.7%) were diagnosed with pulmonary mucormycosis within 90 days after lung transplantation. The mortality was as high as 46.67% (7/15), but if it occurred within 90 days, the mortality reached 70% (7/10). The average interval between transplantation and positive isolation of the pathogen was 112.3 (5-378) days. Conclusions: The clinical and radiographic features of pulmonary mucormycosis after LT were nonspecific. It had a high mortality, especially in those occurred within 90 days after LT. The combination of antifungal therapy and surgical resection may contribute to a better outcome of the disease.

Diabetic patients are considered as a high-risk population for the development of pulmonary tuberculosis (PTB). Usually, PTB is found predominantly in the upper lobes. Lower lung field tuberculosis occurs but is often misdiagnosed as pneumonia, carcinoma, or lung abscesses. In a number of published comparative studies, chest X-ray images from patients having PTB with diabetes mellitus (DM) have been described as ‘atypical’, mainly because they frequently involve the lower lung fields, often with cavities.[12] A higher frequency of multi-lobar involvement has also been described among PTB with DM patients.[1] However, other authors have been unable to find differences in the chest X-ray patterns of pulmonary tuberculosis in diabetic and non-diabetic patients.[3] Thus, whether diabetic subjects present atypical radiological presentation of pulmonary TB is still controversial. We studied 50 patients with pulmonary tuberculosis with or without extra pulmonary tuberculosis having DM. All other forms of extra pulmonary tuberculosis, and HIV seropositive patients were excluded from the study to allow better data comparison. All were subjected to sputum smear for AFB examination, X-ray chest PA view and hematological investigations. Bronchoalveolar lavage and mantoux test were performed only in selected patients. Patients were considered to have a diagnosis of diabetes mellitus if they were receiving insulin or an oral hypoglycemic agent at the time of hospital admission or were found to have two or more fasting blood glucose levels greater than 140 mg%. Upper lung field tuberculosis was defined as tuberculosis involving upper zone. Lower lung field tuberculosis was defined as tuberculosis involving the middle zone and/or lower zone. Cavitation was considered to be present only when its diameter was more than 2 cm. We found that there was a higher involvement of lower lung field (84%) as compared to upper lung field (16%). Bilateral involvement was present in 32% while unilateral involvement was present in 68%. Ten patients out of the 50 had cavitary disease. Cavitary lesions were more frequently confined to lower lung field (80%). Nodular lesions were found in 36%, exudative lesions were found in 22% and mixed lesions were found in 22%. There had been much debate concerning the atypical radiographic findings of TB. Some authors[3] have reported no major differences while others[4] have reported a higher involvement of the lower lung fields. Our study supports that tuberculosis tends to occur predominantly at the lower lung fields in patients with diabetes. Some of the previous studies have reported cavitary lesions to be more common among diabetic patients.[2] Some studies[1] have reported higher frequency of multiple cavities among diabetic patients. But this was not observed in the current study. Reasons for atypical radiological images in tuberculosis patients with associated diabetes are not clear. We conclude that the patients with tuberculosis and DM are more likely to present with atypical radiological images. Among diabetic patients presenting with lower lung field lesions, possibility of TB should always be considered for prompt diagnosis and management.

A 43-year-old female patient is being followed up with a diagnosis of rheumatoid arthritis. She presented with ulcerated lesions on the lower extremity, diffuse subcutaneous nodules, dyspnea, hemoptysis, and fever. Cavitary lesions were detected on the chest X-ray and thoracic computed tomography (Figure 1). The biopsy sample taken from the lesion in the lung was interpreted as “tumor necrosis”. The biopsy sample from subcutaneous nodules was interpreted as ”T-cell/histiocyte-rich large B-cell lymphoma”. There may be some similarities between various lung cavitary lesions, knowledge of the possible causes and a systematic approach will help to narrow down the huge list of differential diagnoses. CAVITY mnemonics can be used for diseases that may cause cavitary lesions in the lung (Table 1) (1). Pulmonary cysts are mimics of emphysema, cystic bronchiectasis, and bullous lung cavitary lesions, and before diagnosing a cavitary lesion, it should be ensured that it is not one of these mimics.

NECROTIZING PNEUMONIA SECONDARY TO CANDIDA INFECTION IN A PATIENT WITH HISTORY OF ALCOHOL ABUSE REQUIRING LOBECTOMY AND ANTIFUNGAL THERAPY