Context: Nasal chondromesenchymal hamartoma is a benign mass lesion of the nasal cavity predominantly described in young infants. These unusual lesions are composed of a proliferation of mesenchymal and cartilaginous elements. Their pathogenesis is unknown, but they may be derived from embryologic rests. To our knowledge, only 1 case in an older child has been reported, and no cases have been reported in adults.
Objective: To report 4 cases of nasal chondromesenchymal hamartoma occurring in older children and adults, including immunohistochemical analysis of these unusual lesions.
Design: Cases identified from our archives were examined to confirm the diagnosis of nasal chondromesenchymal hamartoma. Immunohistochemical analysis was performed using a panel of antibodies (epithelial membrane antigen, smooth muscle actin, all muscle actin, cytokeratin, S100, and KP1) to evaluate for epithelial, smooth muscle, neural, chondroid, and histiocytic differentiation.
Results: Four cases of nasal chondromesenchymal hamartoma in patients of 11, 69, 17, and 25 years of age demonstrated histologic evidence of mesenchymal and cartilaginous elements underlying a chronically inflamed respiratory mucosa. Bony and adipose elements and rare glandular elements were interspersed. Cartilaginous elements stained strongly with S100, whereas mesenchymal regions showed variable and weaker staining. Smooth muscle differentiation was seen primarily in the mesenchymal areas. Epithelial membrane antigen was focally positive in all cases.
Conclusions: Nasal chondromesenchymal hamartomas can rarely occur in the older child and adult. Mesenchymal areas show both myofibroblastic and cartilaginous differentiation. We speculate that inflammation or a recapitulation of developmental signals may be components in the pathogenesis of these lesions.