FLASHPATHH a z e m A l i

DIFFUSE PULMONARY

LYMPHANGIOMATOSIS

H a z e m A l i

CLINICAL• Rare disease characterized by diffuse proliferation of

abnormal, complex lymphatic channels– If localized (focal) lesion lymphangioma

• Typically presents in children and young adults– Similar picture of asthma (dyspnea, wheezing, cough)

• Often complicated by recurrent chylous pleural effusions and recurrent infections

• Slowly progressive and fatal (from respiratory failure)

CLINICAL

Treatment:• Supportive• Treatment of recurrent pleural effusion

– Pleurocentesis– Pleurodesis– Pleurodectomy– Ligation of thoracic duct

• Surgical resection for localized disease• Lung transplantation 

GROSS• Firm, lobulated lung

• Chylous pleural effusion can be seen

• Subpleural and septal thickening

MICROSCOPY

• Pattern:– Proliferation of dilated lymphatic channels– Lined by flat endothelial cells– Surrounding bundles of spindle cells (smooth muscle)– Expand (widen) surrounding connective tissue

• Distribution:– Sub-pleural– Interlobular septa– Peri-bronchovascular

MICROSCOPY

Variant:

• May show hemorrhagic "kaposiform" component– Compressed vascular channels– Plump spindle cells– Hemosiderin

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 Lymphangiectasis:

– Expansion of sub-pleural, Interlobular septa, and peri-bronchovascular connective tissues by:• Dilated lymphatic channels (without proliferation)

• Lymphangioleiomyomatosis:– Occurs only in women of reproductive years– Increased smooth muscle fibers which are HMB45 positive

• Kaposi Sarcoma:– HHV8 positive

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