FlashPath - Lung - Mesenchymal Cystic Hamartoma
Transcript of FlashPath - Lung - Mesenchymal Cystic Hamartoma
FLASHPATHH a z e m A l i
MESENCHYMAL CYSTIC
HAMARTOMAH a z e m A l i
CLINICAL• Very rare
• Benign
• Indolent course– Takes many years to become clinically evident (age range 1 – 50 years)– Creates little disability, even when they are numerous and large
• Can present with cough, chest pain, spontaneous pneumothorax
• May represent the missing link between the higher forms of “cystic adenomatoid transformation” and the lower forms of “pleuropulmonary blastoma”
GROSS• Bilateral
• Multiple
• Cysts (arrowhead) and nodules (arrows)– Cysts are variably sized, thin-wall
MICROSCOPY• Cysts:
– Lining: Respiratory epithelium• “pseudostratified columnar ciliated”
– Wall: Cambium layer• “primitive mesenchymal cells”
• Nodules:– Solid growth of the same primitive mesenchymal cells
• Mature stromal components (e.g., cartilage, smooth muscle, or fat) can be focally seen
• Neither the epithelial nor the mesenchymal cells had malignant features
DIFFERENTIAL DIAGNOSIS“ O t h e r c o n g e n i t a l / c y s t i c l u n g d i s e a s e s ”• Congenital:
– Bronchogenic cysts– Congenital pulmonary cysts– Congenital pulmonary airway malformation “especially type 4”– Congenital lobar emphysema– Pulmonary sequestration
• Acquired:– Emphysema– Healed abscess– Honeycombing
• Mixed:– Cystic fibrosis
DIFFERENTIAL DIAGNOSISPleuropulmonary Blastoma• Occur at an early age (median age of 2 years at presentation)
• Have both cystic and solid lesions macroscopically
• The cyst is composed of small primitive malignant cells lined by normal respiratory epithelium
• Unlike MCH, the mesenchymal cells have high proliferating activity– foci of differentiated sarcomatous elements (e.g., rhabdomyosarcoma,
chondrosarcoma, or osteosarcoma) may be found
DIFFERENTIAL DIAGNOSISPulmonary hamartoma• Solitary
• Solid nodule (No cysts)
• Formed of mature mesenchymal tissue (Not primitive)
• Nodules are separated by clefts lined with respiratory epithelium
DIFFERENTIAL DIAGNOSISIn females, metastatic low-grade endometrial stromal sarcoma must be excluded before diagnoses of mesenchymal cystic hamartoma
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H a z e m A l i