Granular-cell odontogenic cyst

Granular-cell odontogenic cyst An

unreported

odontogenic

lesion

Lionel Gold, D.D.S.,” and Thomas Christ, D.D.S.,** SCHOOL

OF DENTAL

MEDICINE,

UNIVEXSITY

Philadelphia,

Pu.

OF PESXYLVANIA

I

n recent years a number of previously unrecognized or poorly delineated odontogenic lesions have been documented and defined. The inductive effects of odontogenic epithelium and connective tissue are such that a large series of malformations and neoplastic combinations is possible. One might arrange a “periodic table” of odontogenic lesions and reasonably expect to fill in the missing spaces. The purpose of the present report is to present an undescribed cystic odontogenic lesion which we have had the opportunity to study. For obvious microscopic reasons, the lesion is called granular-cell odontogewic cyst. MATERIAL

AND

METHOD

The material, a soft-tissue mass fixed in neutral formalin and measuring about 1.0 by 0.9 by 0.6 cm., was submitted to the Diagnostic Laboratory Service of the School of Dental Medicine. The lesion was bisected along its greater diameter and was found to have a central cavity. Sections were prepared in routine fashion and stained with hematoxylin and eosin for study. Cursory microscopic examination revealed unusual histologic features. The specimen then was cut serially to the ends of the blocks for detailed study. Every tenth section was stained with hematoxylin and eosin, and several were stained with periodic acid-Schiff stain. A few sections of the lesion and of a granular-cell ameloblastoma were mounted on the same slide and stained as above for direct comparison. CASE REPORT The patient, a 3%year-old Caucasian woman, was referred to an oral surgeon for excision of a painless mass on the left lingual surface of the mandible in the premolar region. The *Deparbment of Pathology, School of Dental Medicine, University of Pennsylvania, and Department of Surgery, Hahnemann Medical College and Hospital, Philadelphia, Pa. **American Cancer Society Fellow in Oral Pathology, University of Pennsylvania. Present address: Department of Pathology, Dental School, Emory University, Atlanta, Ga.

437

438

Gold and Christ

Oral Surg. March, 1970

e

Fig. 2. Radiograph Pig. 2. Preoperative

taken on Feb. 5, 1965. radiograph taken on Oct. 8, 1965.

Fig. 3. Low-power photomicrograph showing lining cells may be seen protruding into lumen.

topography

of thick-walled

cyst. Masses of

lesion had been first noted in February, 1965, and was said to have been about the size of a “pea.” It had enlarged to its present size in about 6 months. Clinical examination showed the lesion to be about 2 cm. in size, blue in color, and firm to palpation. Brown fluid was aspirated from its interior. Radiographic examination revealed a radiolucent lesion which apparently had increased rapidly in size since a previous radiographic examination 8 months before (Figs. 1 and 2). The Iesion was enueIeated in October, 1965. A clinical diagnosis of lateral root cyst was made.

Volume Number

Fig. (Medium

29 3

4. Portion power. )

E’iy. 5. Stratified lumen. (Low power.)

HlSTOLOGlC

of cyst

lumen

odontogenic

is lined

epithelium

by stratified

of granular

small

odontogenic

type lined the greater

epithrlial

cell>.

portion

of tho

STUDY

Sections of the specimen showed an irregularly ovoid, cystic, soft-tissue mass which maintained its cystic configuration to the ends of the blocks. A lumen was centrally placed and roughly followed the contours of the tissue mass; hovvever, one block showed the lumen opening to the exterior. Connective tissue was circularly oriented in a thick capsular manner (Fig. 3). Two types of odontogenic epithelium lined the lumen and protruded into it in a stratified manner, with layers varying from four to fourteen cells in thickness. Some areas of the lumen were lined with small odontogenic epithelial cells which kept their compact scanty cytoplasm

440

Oral Surg. March, 1970

Gold and Christ

Fig. 6

Fig.

Y

Figs. 6 and 7. High-power photomicrograph arrangement of odontogenic epithelium.

demonstrating

granular

cells and alveolus-like

and small dark-staining nuclei intact for the entire thickness of their stratification (Fig. 4). These cells were also seen occasionally to form granular cells. However, most areas of the luminal surface were lined with plump epithelial cells with a granular cytoplasm, small nuclei, and distinct borders (Fig. 5). Some cells of the basal layer were vesicular, but most Frequently the basal cells were arranged in demonstrated granules in their cytoplasm. alveolus-like packets (Fig. 13). As the cells moved outward in succeeding layers away from the basement membrane, they became more balloonlike, contained coarser granules, and often lost their cytoplasmic boundaries. A number of these latter cells showed eccentric placement of their nuclei and loss of nuclei (Fig. 7). Sheets of granular cells and granular debris were lying free within the lumen. The connective tissue wall of the cyst was well developed and not prominently vascular; small areas of hemorrhage and inflammatory cells were present. The collagen of the outer layers was circularly arranged as a thick capsule. Occasional small islands of odontogenic epithelium were found in the connective tissue (Fig. 8). In one region, near the periphery

Volume

Number

C;ranula~-cell

29

odontogenic

cyst

441

3

Pig. 8. Small islands (Medium power.)

Fig. 9. Peripheral demonstrating inductive

of odontogenic

epithelium

found

islands of odontogenic epithelium, effect. (Medium power.)

in connective

microcysts,

tissue wall

and connective

of ry4.

tissuca

of the capsule, could be seen numercnls islands of odontogenic epithelium, ameloblast-like in appearance, some of which were undergoing cystic and squamoid changes. The connective tissue around and between some of the islands showed a homogeneous change, probably secondary to an inductive effect (Fig. 9). Of particular interest was an isolated island of granular cells near the periphery but away from the other peripheral and luminal odontogenic epithelial masses. In all respects, this island of granular cells appeared identical to islands typically found in the granular-cell ameloblaatoma (Fig. 10). The island was no longer present as the sections reached the end of the specimen. Comparison of the granular cells of the cyst and of a granular-cell ameloblast,orna revealed identical morphologic features and staining qualities with hematoxylin and eosin

442

Oold

Fig. 20. Island (High power.) and periodic tive.)

Oral Surg. March, 1970

and Christ

of odontogenic

acid-Schiff

stain

epithelial

(PAS).

(The

granular

cells found

at periphery

granular

cells of both lesions

of cyst wall.

were PAS

posi-

DISCUSSION The appearance of this lesion in the premolar area of the mandible is not unusual. The greater number of periodontal and gingival cysts originate in this site. However, the lingual position of the cyst is unusual; most such cysts occupy a buccal position in relation to the mandible. Histologic study of the lesion gives ample proof that it is of odontogenic origin. The presence of the granular cells at the basal-cell level adds credence to the belief that the granules within the cytoplasm represent a metabolic phenomenon rather than a degenerative process. It is possible that the lesion described is merely a monocystic variant of a granular-cell ameloblastoma. If so, however, it is the first one that we have encountered. The granular cells lining the lumen and the definite capsular arrangement of the connective tissue are more eompatibIe with a diagnosis of cyst. It is hoped that a search of material by others may reveal similar examples. Appreciation is expressed describe this case.

to Dr.

Robert

Shields,

Philadelphia,

Pa., for

permission

to