ORAL AND MAXILLOFACIAL PATHOLOGY Editor: Alan R. Gould Abstracts presented at the 58th Annual Meeting and Continuing Education Program of the American Academy of Oral and Maxillofacial Pathology AROMATASE EXPRESSION IN ORAL MUCOSA AND SQUAMOUS CELL CARCINOMA. Y. Cheng, J. Kusek, J. Wright, Baylor College of DentistryeTexas A&M University Health Sciences Center, Dallas, Texas. Aromatase is a cytochrome P-450 enzyme that catalyzes the conversion of androgens to estrogens. It has been found to be expressed not only in the ovaries and testes but also in extragonadal tissues such as skin, muscle, fat, bone, and brain, contributing to the local estrogen formation in these tissues. Its increased expression in breast carcinomas makes it a promising target of chemointervention for hormonal-responsive breast carcinomas. Aromatase expression has never been investigated in normal oral mucosa or in squamous cell carcinomas. Using Western blot and a commercially available aromatase antibody, we found 2 immunoreactive bands of 53 and 60 kDa in dispase-separated oral epithelium obtained from crown- lengthening procedures. The 2 bands were also detected in the primary culture of normal oral epithelial cells (NOEC) from different individuals as well as an oral squamous cell carcinoma (SCC) cell line. However, in NOEC the 60 kDa band was considerably more prominent, while in SCC the 53 kDa was more predominant. Our results indicate that normal oral epithelial cells as well as oral squamous cell carcinoma have the ability to synthesize estrogen. Further immunohistochemical and RT-PCR studies are in progress. INTERNET- AND DVD-BASED INSTRUCTION IN ORAL PATHOLOGY FOR DENTAL STUDENTS. N.J. D’Silva, C.T. Hanks, B. Andrews, University of Michigan, Ann Arbor. In the past 2 years, the Maxillofacial Pathology Laboratory course for dental students at the University of Michigan has been converted from a microscope-based course to an internet-accessible, case-based learning experience that includes a cutting-edge virtual histopathology ‘‘laboratory.’’ Essentially this strategy moved the pathology microscopy course out of the physical laboratory to an online virtual laboratory with an associated pathology workbook. This has saved the students class time, eliminated the need to maintain or replace expensive microscopes, eliminated the space requirement for the laboratory and dramatically improved the quality of slides that students view. The new web-based system has also optimized utilization of faculty. One faculty member now spends 1 hour every other week reviewing the assigned cases and projecting network images of unknown cases in conjunction with high quality virtual ‘‘slides.’’ Bacus laboratories (Lombard, Ill) developed the ‘‘virtual microscope’’ technology that allows tissue sections to be scanned, digitized and visualized at different magnifications on a computer, as one would with a real microscope. Furthermore, we developed a DVD version of the case-based pathology course to provide all students, even those who do not have a rapid internet connection, with off-site access to the pathology course. Conclusions. The online virtual laboratory and workbook give students the opportunity to reinforce concepts that they have passively acquired, by challenging them to ‘‘examine’’ the lesion, develop a differential diagnosis, and discuss further evaluation. This teaching approach utilizes the behavioral, cognitive, and sociocul- tural learning lenses, thereby encouraging the future clinician to be more responsible for his/her learning experience, possibly creating a lifelong learner. The successes and challenges of the virtual laboratory will be discussed. CENTRAL GIANT CELL GRANULOMA OF THE JAWS AND GIANT CELL TUMOR OF LONG BONES. A CLINICOPATHOLOGIC, CYTOMETRIC, AND IMMU- NOHISTOCHEMICAL COMPARATIVE STUDY. M. Al Sheddi, H. Mosadomi, F. Al Dayel, King Saud University, Riyadh, Saudi Arabia. Central giant cell granuloma (CGCG) of the jaws and giant cell tumor of bone (GCT) share a number of similarities and dissimilarities with respect to their histopathologic, cytometric, and immunohisto- chemical features. In the present study the clinical, histopathologic, cytometric, and immunohistochemical features of 18 histologically diagnosed CGCG of the jaws and 22 GCT were compared. The findings on CGCG in particular were analyzed to see if they have any correlation with the so-called clinically aggressive variants of CGCG. CGCG of the jaw showed an early age (55.6% \ 25 years) compared to GCT (50% between 26-38 years). There was a female predilection in both lesions. The mandible was the more common location for CGCG, whereas the femur and tibia were equally affected by GCT. All the lesions were osteolytic in nature; 53.8% of the CGCGs were unilocular with root resorption in 46.2% of the cases. Radiographic features noted in GCT ranged from unilocular to multilocular. Pain and swelling were the usual complaints in both CGCG and GCT. Enucleation and curettage were the most common treatment modalities for both lesions. The recurrence rates of CGCG and GCT were 40% and 45.5% respectively. There were no significant histological differences, with the exception of necrosis, which was higher in GCT. In addition, GCT showed higher mean number of giant cells per measurement field, higher number of nuclei per giant cell, and greater fractional surface area and relative size index compared to CGCG. Both diseases showed similar cellular phenotype with respect to the following cell differentiation markers: Vimentin, S100 protein, CD68, and CD34. There was increased immunoreactivity of GCT to Ki-67, P53, and aSMA. There were no clinical, histologic, cytometric, or immunohistochemical differences doi:10.1016/j.tripleo.2004.06.007 195 Vol. 98 No. 2 August 2004