Differential Diagnosis for Cystic Lung Disease on CT Chest

Single Most Likely Diagnosis

• Lymphangioleiomyomatosis (LAM): A rare lung disease characterized by the proliferation of smooth muscle-like cells, leading to the formation of cysts. It predominantly affects women of childbearing age and can be associated with tuberous sclerosis complex. The presence of uniform, thin-walled cysts distributed throughout the lungs is suggestive of LAM.

Other Likely Diagnoses

• Pulmonary Langerhans Cell Histiocytosis (PLCH): A rare disease characterized by the proliferation of Langerhans cells in the lung, leading to cyst and nodule formation. It is often associated with smoking and can present with a combination of cysts and nodules on CT.
• Cystic Fibrosis: An inherited disorder that causes severe damage to the lungs, digestive system, and other organs in the body. Cystic fibrosis affects the cells that produce mucus, sweat, and digestive juices, causing these fluids to become thick and sticky. This can lead to the formation of cysts and bronchiectasis in the lungs.
• Emphysema: A condition in which the air sacs of the lungs are damaged, leading to breathlessness. While not typically thought of as a cystic lung disease, advanced emphysema can result in large bullae that may appear cystic on CT.

Do Not Miss Diagnoses

• Pneumocystis Jirovecii Pneumonia (PCP): An opportunistic infection that can cause cystic changes in the lungs, particularly in immunocompromised patients. It is crucial to consider PCP in patients with HIV/AIDS or those on immunosuppressive therapy.
• Cystic Metastases: Certain malignancies, such as sarcomas or metastatic renal cell carcinoma, can present with cystic lung lesions. Recognizing these as potential metastases is critical for appropriate management.

Rare Diagnoses

• Birt-Hogg-Dubé Syndrome: A rare genetic disorder characterized by the development of benign tumors in the hair follicles (fibrofolliculomas), an increased risk of kidney cancer, and the presence of lung cysts. The lung cysts in Birt-Hogg-Dubé syndrome can be variable in size and are often basilar predominant.
• Neurofibromatosis Type 1 (NF1): A genetic disorder that can affect many areas of the body, including the lungs. While less common, NF1 can be associated with cystic lung disease, among other pulmonary manifestations.
• Tuberous Sclerosis Complex (TSC): A genetic disorder that causes non-cancerous tumors to form in many different organs, including the lungs. TSC can lead to the development of lung cysts, particularly in women, and is associated with LAM.