-Age, gender and location
One-hundred and thirty out of 164 (79.3%) specimens obtained from 123 patients (47 males, 76 females; male to female ratio = 1:1.6; mean age 23.2 years) were classified as DFs (DF group). Lesions diagnosed as DCs (DC group) were 23 (14%) and they were removed from 22 patients (6 males and 16 females, mean age 35.7 years). For 11 out 164 cases (6.7%), the diagnosis was questionable since focal areas of stratified squamous epithelium suggestive of DC, were observed within the context of a DF ().
Subclassification of 164 cases according to histopatological diagnosis.
Among 154 patients, 76 (43.3%) and 51 (31.1%) were in the second and in the third decade of life, respectively.
Seventy-eight percent (128 out of 164) of the specimens were associated with lower impacted third molar teeth (66 cases associated to 4.8; 62 cases associated to 3.8) while 4.3% (7 out of 164) and 3.6% (6 out of 164) were associated with upper canine and upper third molar teeth, respectively.
Ninety-eight out of 130 cases (75.3%) in the DF group and 21 out of 23 lesions (91.3%) of the DC group were associated with lower impacted third molars (DF group: 50 cases associated to 3.8; 48 cases associated to 4.8. DC group: 13 cases associated to 4.8; 8 cases associated to 3.8). For 5 cases in the DF group no data on location were available.
-Clinical versus histopathological diagnosis
One-hundred and two out 130 specimens (78.5%) classified as DFs were submitted for histopathological evaluation with a clinical diagnosis of “dental follicle” or “enlarged follicle” associated with an impacted tooth. In one of these cases, a second working diagnosis of “ameloblastoma” was mentioned, while in 2 cases the possibility of a DC was taken into account in the differential diagnosis. In 20 out of 130 cases (15.4%) the clinical diagnosis was “dentigerous cyst” or “follicular cyst” and therefore, not in accordance with the histopathological diagnosis. In one case the clinical diagnosis was keratocyst. Seven surgical specimens were submitted without a working diagnosis.
Fifteen out of 23 lesions (65.2%) histopathologically classified as DCs were submitted with a clinical diagnosis of “dental follicle” while only 6 lesions (26.1%) of the same group had a clinical diagnosis of “dentigerous cyst”. One surgical specimen was provided with a working diagnosis of ameloblastoma while another was reported as “fibrous tissue around the crown of an im-pacted tooth”. Among the group of the histopathologically “questionable” lesions, 8 and 2 out of 11 had a clinical diagnosis of “dental follicle” and “dentigerous cyst”, respectively. One specimen was provided without a working diagnosis.
The most frequent histopathological description of DF includes presence of connective fibrous tissue partially or completely lined by columnar or cuboidal epithelium, representing the reduced epithelium from the enamel organ. Four cases presented distinct myxoid changes of the connective tissue while in 47 cases (36.1%) presence of a chronic inflammatory infiltrate, ranging from mild to severe, was reported. Reactive and hyperplastic changes of the epithelium without cellular atypia were described in 6 cases. Two cases were characterized by the presence of focal calcifications. Small OE remnants in the connective tissue were reported in 27 DFs (Fig. ). Histopathological reevaluation of the specimens, revealed presence of FA in one case. FA islands were characterized by a fairly classic stellate reticulum surrounded by a single layer of tall, columnar, ameloblastic-like cells with nuclei at the opposite pole to the basement membrane. FAs were completely embedded in the connective tissue and they were not contiguous with the lumen of the lesions (Figs. ,).
Proliferation of normal odontogenic epithelium in a dental follicle (H.E.; orig. magn. x100).
Foci of ameloblastomatous epithelium in a dental follicle (H.E.; orig. magn. x25).
High power view of ameloblastomatous island (H.E.; orig. magn. x200).
In the group of DCs, the most frequently reported findings include the presence of a connective fibrous capsule lined by stratified squamous epithelium. Presence of chronic inflammatory infiltrate was reported in 7 cases while 3 cases presented myxoid changes in the connective tissue. One case was characterized by the presence of hyperplastic epithelium, while in another case, focal epithelial features of a keratocyst were reported. Actinomyces colonies were observed in one specimen. FAs were observed in 2 out of 7 cases re-evaluated because of the presence of OE in the connective tissue (Fig. ). OE remnants were also reported in 5 “questionable” lesions.
Ameloblastomatous changes in the wall of a dentigerous cyst (H.E.; orig.magn. x100).
Altogether, presence of small OE rests in the connective tissue was documented in 39 out of 164 (23.7%) specimens.
In no one of the 3 patients with FA, a (recurrent) ameloblastoma was registered in the PALGA database during a follow-up of 6 (case of FA in DF group), 8 and 22 years (cases of FAs in DC group).