Pulmonary mucormycosis mimicking as pulmonary tuberculosis: A rare case report

Pulmonary mucormycosis is a rare disease caused by order Mucorales of class Zygomycetes, affecting immunocompromised individuals, both in developing and developed countries [1]. The term Zygomycosis, which was used for infections caused by fungi of the order Mucorales, has been discarded according to the recent taxonomic literature that abolished Zygomycetes as a class [2]. Mucorales fungi are ubiquitous, saprophytic and not fastidious fungi found on soil or decaying organic matter. The three genera that are most commonly associated with infections in the human, namely, Rhizopus, Mucor and Absidia (Lichtheimia) [3]. Rhino-orbitalcerebral and pulmonary infections are the most common manifestations caused by these fungi by the inhalation of spores. In 1876, the fi rst case of Pulmonary mucormycosis was reported by Furbringer [4 ]. The prevalence of mucormycosis is estimated to be around 70 times higher in India than globally. Diabetes mellitus is the most common risk factor, followed by haematological malignancy and solid-organ transplant. Other risk factors include illicit use of intravenous drugs, prolonged steroid use, persistent neutropenia, desferoxamine therapy. Patients with post-pulmonary tuberculosis and chronic kidney disease are additional emerging risk factors for developing mucormycosis in India [5]. There is spike in the cases of Mucormycosis due to COVID 19 infection as it is associated with impaired immune status in the infected patient. We are reporting a case of Pulmonary mucormycosis in an HIV seropositive patient, which was misdiagnosed as Pulmonary tuberculosis.

therapy) as patient has past history of intravenous drug abuse (heroin addict) 1year back for the duration of 9 months. He was treated for pulmonary tuberculosis thrice in past 3 years. He gave history of smoking for 4-5 years, alcoholic for 5 years. He was taking anti-tubercular treatment (Rifampicin, Isoniazid, Ethambutol, Pyrazinamide) for Pulmonary tuberculosis on clinico-radiological basis for last 10 days.
On examination, patient was emaciated. He was slight dyspnoeic without the use of accessory muscles, with a blood pressure of 120/70 mmHg, pulse rate of 94/min, respiratory rate of 26/min, and saturation of 92% on room air. On general physical examination, clubbing was present. On auscultation, bilateral bronchial breath sounds present on interscapular and infra-scapular areas increase vocal fremitus bilaterally.

Discussion
Mucormycosis is an opportunistic, angio-invasive fungal infection, affecting immunocompromised individuals. It is a rapidly progressive infection associated with high morbidity and mortality. In recent years, it has been observed that the epidemiology of mucormycosis is being changing as incidence has raised with new causative agents and changing susceptible population. It is very high in Asian countries as compared globally. Though diabetes mellitus is most common risk factor found in Asia as well as globally, post-tuberculosis and chronic renal failure are new risk groups emerging in developing countries. The rhino-orbital-cerebral form of mucormycosis is most commonly associated with diabetes mellitus, whereas, pulmonary mucormycosis seen in patients with haematological malignancy and transplant recipients [6]. Other risk factors    include illicit use of intravenous drugs, prolonged steroid use, persistent neutropenia, desferoxamine therapy. In India, Postcovid mucormycosis cases have also been reported due to the ongoing pandemic [7]. The prevalence of mucormycosis is estimated to be around 70 times higher in India than globally, which were estimated to be at 0.02 to 9.5 cases (with a median of 0.2 cases) per 100,000 persons [5,6]. Patients with postpulmonary tuberculosis and chronic kidney disease are the emerging risk factor for developing mucormycosis in this country [5].
In our case, HIV seropositive due to illicit use of intravenous renal, and disseminated mucormycosis [8]. The ROCM type is the most common form of the disease in India, followed by the pulmonary and cutaneous types [9]; however, the pulmonary mucormycosis is the most common clinical presentation in developed countries [10]. Rhizopus arrhizus is the most common cause of mucormycosis in India, other agents like Rhizopus microsporus, Rhizopus homothallicus, and Apophysomyces variabilis are rising [6].
Pulmonary mucormycosis is the rapidly progressive infection that occur after inhalation of spores into respiratory tract or by hematogenous or lymphatic spread [11]. It may present with nonspecifi c symptoms like cough, dyspnoea, chest pain, and fever [11]. Most patients present with fever and haemoptysis which can be massive sometimes. Haemoptysis results from angioinvasion which results in infarction and necrosis of the tissue, can leads to cavitation and haemoptysis, if major vessel gets involved it may be fatal [12].
The diagnosis of mucormycosis is made by histopathology and direct microscopy along with culture of the respective clinical specimens [13]. On histopathological examination, mucormycosis species appear as broad, nonseptate hyphae with right angle branching. Patient suspected of Pulmonary mucormycosis should be differentiated from aspergillosis as on histopathological examination Aspergillus shows regular, septate hyphae with acute angle branching [14].
Radiologically, the appearance of pulmonary mucormycosis is non-specifi c. Chest radiograph is abnormal in >80% of patients [15]. Most common radiographic fi nding include lobar and segmental consolidation, in some patients it can be multi-lobar in distribution. Other fi ndings include groundglass lesions generally progress to consolidation, multiple pulmonary nodule or masses which may have ground-glass halo (halo sign), which may progress to reverse halo sign with central necrosis, rarely cavity formation, and the aircrescent sign. As the fungus is angio-invasive, it causes the vascular fi ndings like pulmonary artery pseudoaneurysms, and abrupt termination of pulmonary artery branch appearing as vascular cut-off sign. It can spread to pleura, chest wall and mediastinum causing lymphadenopathy, surgical emphysema and pleural thickening or effusion. Cavitation is seen in 40% of cases, but the air-crescent sign is rarely seen [16]. The presence of the air-crescent sign is an ominous sign, thus surgical management should not be delayed. High-resolution CT chest is used to determine the extent of disease with high sensitivity in Pulmonary mucormycosis.
In Most importantly, Pulmonary mucormycosis should be differentiated from Invasive aspergillosis so that appropriate treatment should be given for patient's survival [16].
Treatment of pulmonary mucormycosis include medical treatment with the recommended antifungal therapy and extensive surgical debridement [18].