Abstract: Alternaria species is a rare cause of invasive fungal pneumonia, typically described as an opportunistic pathogen, usually seen in immunocompromised patients producing virulent forms of sinus, cutaneous, and ocular infections. Alternaria species sparingly affect immunocompetent individuals and are often managed without any medical interventions. We present a case of invasive fungal necrotizing pneumonia caused by Alternaria alternata species in an immunocompetent 28-year-old male with only a past medical history of well-controlled asthma managed with an as-needed albuterol inhaler. His complaints included worsening foul-smelling productive cough with yellow-dark brown sputum along with subjective fevers, chills, chest pain, and dyspnea for one month. His occupation involved weeding deer fields which involved exposure to dust particles. He reports not using a mask or other protective equipment. He denied recent travel, bird exposure, history of covid infection or family history of malignancy. He initially presented to outside facilities and was started on empiric oral antibiotics like doxycycline and augmentin, however, after failing outpatient therapy, he was referred to a pulmonologist. The pulmonologist ordered a CT chest which revealed a right lower lobe consolidation with cavitation mass. He subsequently underwent bronchoscopy with transbronchial biopsies that were surprisingly negative for malignancy or bacterial infection. During this time, HIV and hepatitis testing along with Interferon Gold testing were performed and were all negative, but patient’s symptoms worsened despite antibiotic therapy in addition to systemic steroids, and as a result, he was admitted to the hospital for further evaluation and management. Patient’s serum IgE level was obtained prior to admission and was found to be elevated at 3000. Fungitell and galactomannan were also significantly elevated. A CT angiogram of the chest obtained during this hospital admission revealed significant progression of right lower lobe consolidation with bronchiectatic changes. Fungal cultures of outpatient bronchoalveolar lavage (BAL) from the bronchoscopy returned positive for Alternaria alternata species. After conferring with pulmonology and infectious disease specialists, the patient was eventually transitioned to intravenous itraconazole along with systemic steroids demonstrated significant clinical improvement and was stabilized for discharge with proper outpatient follow up with pulmonology, infectious disease, and primary care. Althought IgE levels were elevated, a thorough auto-immune workup was obtained and was negative for any auto-immune conditions such as sjogren's disease, systemic lupus erythromatosus, rheumatoid arthritis, scleroderma, and more. Our case highlights the importance of considering occupational hazards in the management of atypical pulmonary pathology in an immunocompetent male. Case Description: Medical History: The patient is a 28 year-old male with past medical history of asthma admitted for sepsis secondary to persistent pneumonia concerning for invasive necrotizing fungal pneumonia. Patient reports the onset of productive cough with malodorous yellow-brown sputum for about one month prior to admission. Patient initially presented to an outside emergency department (ED), where a CT chest was obtained and showed a 4.0 cm mass-like opacity in the basal segment of the right lower lobe of the patient’s lung, patient was discharged on oral doxycycline, as the patient was suspected to have a typical lobar pneumonia from a bacterial infection. Patient’s symptoms did not improve after completing the antibiotic course, and he presented to another outside ED where another CT chest was obtained and showed the same right lower lobe mass, however, it increased in size to 4.2 cm. The patient was then started on oral augmentin and re-presented to his primary care provider who referred him to pulmonology who ordered a repeat CT chest revealing a cavitary right lung mass. Patient underwent bronchoscopy where large mucus plug was identified and transbronchial biopsies obtained were negative for malignancy or bacterial infection. Outpatient HIV/hep/quantiferon gold testing was negative. Serum IgE levels were ordered and were approximately 3,000. Fungal culture from bronchoalveolar lavage were positive for Alternaria. Patient had been on empiric antibiotics for 4 weeks with worsening dyspnea, subjective fever, and chills. On admission, patient was hemodynamically stable. A CT angiogram of chest showed significant progression of right lower lobe cavitation consolidation with bronchiectatic changes. Patient also reported acid reflux-related symptoms with post-tussive emesis and GI was consulted. Infectious Disease was consulted for antifungal assistance. Infectious Disease History: Patient has a history of asthma well controlled with as-needed inhaled albuterol, with only 4 episodes of severe asthma exacerbations requiring steroids four times annually. Patient reports no bird exposure. Patient reports annual cleaning of deer lease areas with weeding leading to dust dispersal into the air, and during these episodes he does not wear a mask or other protective equipment. After an episode of dust exposure, he began developing worsening symptoms. At baseline, he makes balls of brown foul-smelling sputum frequent, especially in the past two years and recently began getting worse. During this period, he denies any hemoptysis, but admits to frequent vomiting secondary to developing gastroesophageal reflux disease from nocturnal coughing spasms in addition to night sweats. Patient presented to an outside emergency department twice and was started on empiric antibiotics which did not improve symptoms, and was eventually referred to a pulmonologist who ordered a CT chest which revealed right lower lobe consolidation with cavitation mass. He subsequently underwent bronchoscopy which he was noted to have partial narrowing and obstruction of the superior segment of right lower lobe of lung. Transbronchial biopsies that were negative for malignancy or bacterial infection; broncho-alveolar lavage (BAL) samples were obtained and eventually were positive for Alternaria alternata species. He was also tested for HIV and hepatitis along with Interferon Gold testing for tuberculosis (TB), all of which were negative. Patient also had an IgE level obtained which was elevated at 3000. Despite the elevated immune marker, laboratory testing at MCFW revealed negative titers for auto-immune conditions such as Sjogren's disease, scleroderma, Systemic Lupus Erythematosus (SLE), and rheumatoid arthritis (RA) although anti-CCP titers were elevated. When patient’s symptoms continued to persist despite empiric antibiotics, steroids, and inhalers, he was admitted to the hospital for further evaluation. He was started on intravenous vancomycin, cefepime, and eventually itraconazole, and oral steroids were discontinued. After BAL cultures were positive for Alternaria alternata, the the patient was continued on these antibiotics and antifungals and discharged on intravenous antibiotics with close outpatient follow-ups to his pulmonologist, infectious disease specialist, and primary care doctor, demonstrating significant clinical improvement. Discussion: Our case involved an immunocompetent young male with a known history of asthma who was admitted for persistent pneumonia. Outpatient bronchoscopy results revealed a fungal pneumonia with Alternaria species. Alternaria species are increasingly found to be the etiology of fungal sinus, pulmonary, and central nervous system disease in transplant and leukemic patients. The incidence of Alternaria pneumonia is not well documented given the challenge of diagnosis.