The goal of this observational study is to learn about sarcoidosis development after COVID-19 infection.

The main question it aims to answer is:

• prevalence of Sarcoidosis among patients previously infected with COVID-19.

Participants will:

• provide previous positive RT-PCR for COVID-19
• Have computed tomography of the Chest with suggestive findings of sarcoidosis
• Have bronchoscopic guided biopsies and pathological analysis to detect number of patients with sarcoidosis.

This prospective cross sectional study was performed on a total of 55 patients with mediastinal and /or hilar lymphadenopathy with or without lung infiltrates referred to Bronchoscopy unit , Chest department, Ain-Shams University hospital for biopsy taking and diagnosis.

All patients were subjected to the following : history taking , clinical examination , radiological assessment by computed tomography (CT )chest , fiberoptic bronchoscopy where biopsies were taken either by conventional-Trans-bronchial needle aspiration (c-TBNA) , endo-bronchial ultrasound (EBUS-TBNA) or direct forceps biopsies and sent for histopathological examination and if the patient had past history of COVID-19 infection with previous positive reverse transcriptase- polymerase chain reaction assay (RT-PCR).

Inclusion Criteria:

• All adult patients with previous positive RT-PCR for COVID -19 and CT chest findings of mediastinal and or hilar lymphadenopathy with or without lung infiltrate will be included. .

Exclusion Criteria:

• Patients younger than 18 years old Patients
• Patients refuse to participate in the study
• Patients previously diagnosed as sarcoidosis

Patients previously diagnosed as COVID -19 by RT-PCR ,with mediastinal or hilar lymphadenopathy with or without lung infiltrates referred to bronchoscopy unit ,Chest Department, Ain-Shams University Hospital for diagnosis.