Epithelioid osteoblastoma of maxilla: A rare and aggressive variant of a benign neoplasm at an uncommon site

Abstract

Osteoblastoma (OB) is an uncommon benign bone-forming tumor accounting for <1% of all bone neoplasms. Unlike conventional OB, its small subset variant “Epithelioid osteoblastoma (EO)” is characterized by its propensity for local invasion and recurrent behavior. This rare variant of an uncommon tumor when occurs in an atypical site can lead to diagnostic problems more so due to ambiguous clinico-radiologic presentation. This was what faced in the present case of 18-year-old female with a swelling in upper jaw. OB is usually more common in males and involves primarily the posterior element of the spine and the sacrum (40–55%). Less frequently, long bones of limbs are involved. Clinical, radiological and histopathological correlation in this case guided us to reach at right diagnosis of EO which helped the patient in getting correct treatment which involves surgical excision over conventional curettage. The purpose behind this case presentation is to improve the awareness about this recurrent tumor variant which has many close differentials including well-differentiated osteoblastic osteosarcoma.

Clinicopathologic study of 6 cases of epithelioid osteoblastoma of the jaws with immunoexpression analysis of FOS and FOSB

“…14 Few cases have been reported in the jaws, with the mandible more frequently affected than the maxilla. 5,10,[14][15][16][17][18][19] In our series, 4 tumors (67%) affected the mandible, and only 2 (33%) affected the maxilla. Upon review of the literature, we found some reports of epithelioid/aggressive osteoblastomas showing microscopic features similar to our cases.…”

“…Variable levels of mineralization and different stages of maturation of the calcified component were present, and peripheral maturation of "blue bone" to trabeculae of woven bone was a frequent finding. 18,19 Two of our cases showed a different concentric pattern of the mineralized component, resembling the so-called Liesegang rings. Osteoclastlike multinucleate giant cells, which have been frequently reported, 15,18,19 were observed occasionally in our cases.…”

“…18,19 Two of our cases showed a different concentric pattern of the mineralized component, resembling the so-called Liesegang rings. Osteoclastlike multinucleate giant cells, which have been frequently reported, 15,18,19 were observed occasionally in our cases.…”

“…10,15,18,20 The slow tumor growth was frequently associated with pain, 10,15,18-21 facial asymmetry, and tooth displacement. 10,19 On radiographic images, the lesions often have a mixed radiolucent/radiopaque appearance with well-defined borders, consistent with its benign nature. 5,10,15,19 Periosteal reaction and peripheral bone sclerosis 5 have also been reported.…”

“…10,19 On radiographic images, the lesions often have a mixed radiolucent/radiopaque appearance with well-defined borders, consistent with its benign nature. 5,10,15,19 Periosteal reaction and peripheral bone sclerosis 5 have also been reported. Well-defined margins were observed in only 2 cases in our series.…”