Pleomorphic adenoma of the submandibular salivary glands with marked ossification

This article describes an unusual case of pleomorphic adenoma arising in the submandibular salivary glands that was associated with marked ossification. CT scan showed an irregular high-density mass in the left submandibular region. Histologic examination of the resected mass revealed a well-circumscribed pleomorphic adenoma with chondroid tissue intermingled with glandular and trabecular epithelial components. Irregularly formed osseous tissue was present in the chondroid tissue. The osseous tissue showed bone matrix on von Kossa's staining. Alkaline phosphatase expression was restricted to the vicinity of osseous tissue. Tartrate-resistant acid phosphatase-positive osteoclasts were observed at the periphery of the osseous tissue. CD34 staining demonstrated many microvascular vessels in both the chondroid and osseous tissues. We conclude the osseous tissue in pleomorphic adenoma was bone in nature, and via the process of endochondral ossification most likely depended on angiogenesis.