PathDojo Flashcards: Pneumothorax & Lung Conditions

Pneumothorax

• Increased levels of interleukin-5 and eosinophils found in pleural fluid.

Alveolar Proteinosis

• Characterized by deposition of PAS positive material in alveoli.
• Results from impaired turnover of surfactant.
• Involves type II pneumocytes and macrophages.

Sclerosing Hemangioma

• Strongly and consistently stains for TTF-1 and EMA.
• Positive for pan-cytokeratins and CK7.
• Misnomer for sclerosing pneumocytoma.
• Four histological patterns: papillary, sclerosed, hemorrhagic, and solid.
• Composed of papillae, round cells, and cuboidal cells; benign but can mimic malignancy.

Carcinoid Tumor

• Positive for synaptophysin, chromogranin, and cytokeratins.

Mesothelial Cells Identification

• Identified through IHC markers: WT-1, calretinin, D2-40, desmin.

Mesothelioma Identification

• IHC markers include WT-1, calretinin, D2-40, and EMA.

Adenocarcinoma Identification

• Stains for Napsin A, Ber EP4, CK7, TTF-1, and sometimes CK20.

Asbestos Exposure

• Remote exposure results in benign parietal pleural plaques, made of hyalinized collagen.
• Common in individuals with a history of construction work.

Clear Cell (Sugar) Tumor of the Lung

• Stains positive for HMB45 and S100.
• Part of PEComa family, which includes lymphangioleiomyomatosis, angiomyolipoma, and others.
• Positive for melanocytic and smooth muscle markers; generally benign.

Clear Cell Lung Tumor

• Contains PAS positive glycogen and is classified as generally benign.

Tuberous Sclerosis

• Associated with TSC1 and TSC2 mutations in PEComas.

Bronchogenic Cysts

• Most common at the carina level; composed of benign epithelium with ciliated cells.

CMV Pneumonia

• The notes do not provide specific details on this condition.

Lipoid Pneumonia

• Characterized by empty spaces (lipids) and inflammatory cells.

Lung Adenocarcinomas

• Typically stains with TTF-1, Napsin A, CK7, and Ber EP4.
• Mucinous or mixed components may also show CK20 positivity.

Pulmonary Langerhans Cell Histiocytosis

• Most prevalent in young to middle-aged adults with a smoking history.
• Langerhans cells demonstrate positivity for CD1a and S100 via IHC.
• Electron microscopy reveals Birbeck granules resembling tennis rackets.

KRAS Mutations

• More prevalent in smokers.

EGFR Mutations

• More common in female non-smokers, particularly with adenocarcinoma featuring bronchioalveolar characteristics; responsive to anti-EGFR therapy.

ALK-EML4 Mutations

• Frequent in non-smokers and light smokers, younger patients, and associated with acinar morphology; linked to resistance against EGFR inhibitors.