Nasal inverted papilloma expresses the muscle segment homeobox gene Msx2: possible prognostic implications.

Nasal inverted papilloma is a rare benign tumor of epithelial origin with aggressive evolution, bone destruction, recurrence, and malignant transformation. Msx2 is a homeobox gene implicated in organ development, bone metabolism, and tumorigenesis. Using reverse transcriptase-polymerase chain reaction and immunohistochemistry, Msx2 expression was examined in nasal inverted papilloma and in nontumorigenic tissue counterparts. For the first time, Msx2 was detected in all inverted papillomas but not in the nasal polyps or in the normal mucosa. The protein expression level was directly and significantly associated with tumor recurrence. Furthermore, Msx2 was associated with bone resorption markers receptor activator of nuclear factor-kappa B ligand and tartrate-resistant acid phosphatase, suggesting a role in osteolysis. In conclusion, Msx2 expression may represent a useful prognostic marker in inverted papilloma.