FLASHPATHH a z e m A l i

PULMONARY LYMPHANGIEC

TASISH a z e m A l i

CLINICAL• Rare disease characterized by abnormal dilatation of

pulmonary lymphatics, but without proliferation (no increase in lymphatics number)

• Present early in life with neonatal respiratory distress, hypoxia and cyanosis

• Bilateral Chylothorax is common finding

• Often fatal (poor prognosis)

CLINICALEither primary or secondary (Faul Classification):

• Primary:– Primary developmental defect of the pulmonary lymphatics

• Secondary:– Secondary disorders that impair lymphatic drainage / increase lymph

production• including surgery, radiation, infection, tumor, trauma

GROSS

• Firm, heavy and noncompliant lungs

• Bilateral milky (lymph) pleural effusion can be seen

• Numerous dilated cystic spaces (lymphatics) seen in:– Sub-pleura– Interlobular septa– Peri-bronchovascular

MICROSCOPY

• Pattern:– Multiple cystic spaces (dilated lymphatic vessels)– Lined by flat endothelial cells– Expand (widen) surrounding connective tissue

• Surrounding tissues:– Sub-pleural– Interlobular septa– Peri-bronchovascular

SPECIAL STUDIES• Endothelial cells are positive to Vascular markers

– Commonly used: CD31, CD34, Factor VIII• “Cytoplasmic and Membranous”• CD31 is the most sensitive and specific vascular marker

– Less commonly used: Ulex europaeus I, CD141 (thrombomodulin), Fli-1

• Also positive to D2-40 (Podoplanin)– “Membranous”– Specific to lymphatic endothelium

DIFFERENTIAL DIAGNOSIS• Pulmonary Lymphangiomatosis:

– Expansion of sub-pleural, Interlobular septa, and peri-bronchovascular connective tissues by:• Increased number of dilated, anastomosing lymphatic channels

• Pulmonary interstitial emphysema:– Expansion of sub-pleural, Interlobular septa, and peri-bronchovascular

connective tissues by multiple cystic spaces that:• Contain air (not lymph)• Do NOT have lining (negative for vascular markers and D2-40)

DIFFERENTIAL DIAGNOSIS“ O t h e r c y s t i c l u n g d i s e a s e s ”• Congenital:

– Pulmonary sequestration– Congenital pulmonary cysts– Congenital pulmonary airway malformation– Congenital lobar emphysema

• Acquired:– Emphysema– Healed abscess– Honeycombing

• Mixed:– Cystic fibrosis

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