oral surgery oral medicine oral pathology

With sections on oral and maxillofacial radiology and endodontics

oral surgery

Editor: ROBERT B. SHIRA, DDS

School of Dental Medicine Tufts University I Kneeland Street Boston, Massachusetts 0211 I

Recurrence of keratocysts and decompression treatment A long-term follow-up of forty-four cases

Niels Br#ndum, DDS, DOS,a and Vagn Juhl Jensen, MD,b Odense, Denmark

Recurrence was found in eight cases (18%) in a group of 44 patients (22 male) with odontogenic keratocysts treated at the Department of Oral Surgery and Oral Medicine, Odense University Hospital, from 197 1 to 1983. All these recurrences were found in cysts with parakeratotic, thin, bandlike epithelium with palisade-like basal cells (Forssell group la). In 12 large cysts the use of a polyethylene drainage tube implanted at cystotomy and biopsy some months before primary cystectomy resulted in considerable

reduction in the cystic lumen and also in alteration of the thin, fragile cystic epithelium into thick, solid cystic epithelium with no adhesion to the adjoining structures. No recurrence was seen in these 12 patients after an observation period of between 7 and 17 years. The decompression treatment seems to reduce the tendency to recurrence of the odontogenic keratocyst, which is far more important than the advantages to the surgeon of surgical simplicity and safety, and to the patient of less discomfort and pain. (ORALSURCORALMEDORALPATHOL~~~~;~~:~~~-9)

T he recurrence rate of odontogenic keratocysts (OKCs)’ has been high since the first thorough inves- tigation of these cysts was reported in 1963.2 Recur- rence has been described as late as 37 years after pri- mary cystectomy.3 It has been suggested that recur- rence is a consequence of technical difficulties in radical cystectomy, because of the cobweblike cystic epithelium or because of the localization of the cyst to inaccessible sites or to adhesions. Attempts have been made to reduce this high recurrence rate by im- proved surgical techniques, such as removal of super- adjacent mucosa, smoothing of the osseous wall of the cystic cavity, resection of neighboring parts of the mandible, tanning of the epithelial lining of the cyst with Carnoy’s solution, cryotherapy, and marsupia-

*Department of Oral Surgery and Oral Medicine. bDepartment of Oral Pathology. 7/12/31010

lization.4-‘0 A follow-up period of at least 5 years is advisable because most recurrences develop within the first 5 years of the initial cystectomy.5y l1

The aim of the present investigation has been to carry out a long-term follow-up of cases of OKCs treated at the Department of Oral Surgery and Oral Medicine, Odense University Hospital, with special attention given to the relationship between recur- rence, histologic findings, and surgical technique.

MATERIAL AND METHODS

A total of 51 patients with OKC were treated dur- ing the period from 1971 to 1983. Two patients with metaplasia of the OKC developing into ameloblas- toma were excluded, as were five with nevoid basal cell carcinoma syndrome, which carries an increased ten- dency toward recurrence. i2*13 Thus 44 patients re- mained: 22 females with a mean age of 47 years (range 9 to 87 years) and 22 males with a mean age

265

266 Br#ndum and Jensen ORAL SURG ORAL MED ORAL PATHOL September I99 I

Fig. 1. End of polyethylene tube is expanded by heating above spirit lamp.

of 43 years (range 18 to 76 years). The male/female ratio was thus 1: 1.

In 32 cases the diagnosis of OKC was based on a biopsy taken from material obtained by primary cys- tectomy. Twelve OKCs were diagnosed at cystotomy and biopsy of large cysts in connection with insertion of a polyethylene drainage tube for decompression. All 44 cysts were classified histopathologically ac- cording to Forssell groups I to V.14

The Forssell grouping is as follows:

la. Thin, bandlike parakeratotic cyst epithelium; basal cells are cuboidal or columnar, accentuated, and pal- isade-like

Ib. Epithelium composed mainly of basal cell layer only; basal cells accentuated

II. Orthokeratotic cyst epithelium with distinct stratum granulosum; accentuation of basal cells is not pro- nounced

III. Cyst epithelium exhibiting areas of orthokeratiniza- tion and nonkeratinization

Fig. 2. Collar is molded by pressing the heated tip against cold glass plate.

Fig. 3. Polyethylene drainage tubes produced in various lengths and with varying angles of collars.

IV. Parakeratotic cyst epithelium resembling the oral mucous membrane

V. Cyst epithelium thin and parakeratotic; basal cells not accentuated

Our standard treatment has been primary cystectomy with smoothing of the osseous wall of the cavity; this was employed in 32 cases. One of these cases required electrocauterization to arrest bleeding from the man- dibular canal.

A polyethylene drainage tube is inserted in large follicular or residual cysts as a routine procedure in connection with cystotomy and biopsy before cystec- tomy is done. This results in decompression and a subsequent reduction in the size of the cystic cavity.i5 In 12 cases where biopsy showed OKC, a drainage tube was inserted 1 to 14 months (mean 10 months) before primary cystectomy.

The drainage tubes are produced from small lengths of polyethylene tubing (outer diameter 2.3 mm, lumen 1.6 mm) by heating the ends in a spirit lamp (Fig. 1) and then pressing them against a cold glass plate, thus making a collar at both ends (Fig. 2). Such

Keratocyst recurrence and decompression 267 Volume 72 Number 3

6 ,’ II

5 I

50 60 70 60

Years

Fig. 4. Distribution of OKCs according to age and sex.

Number

16.

la lb 2 3 4 5

Forssell groups

Fig. 5. Distribution of OKCs according to sex and Forssell group.

Fig. 6. Polyethylene drainage tube in upper frontal re- gion, kept in position by collars.

tubes can be produced in various lengths and with the collars at varying angles (Fig. 3). The tube selected for a particular case should be as short as possible. It is kept in place by means of the collars. The tube is introduced through an incision in the mucosal flap that is elevated to gain access to the cyst for cysto- tomy and biopsy. After the sutures in the mucosal flap are removed 5 to 8 days after cystotomy, the patient is instructed to flush the cavity daily through the tube with a 0.1% solution of chlorhexidine gluconate until cystectomy can be carried out; this is done with a normal syringe and a thin blunt hypodermic needle.

The reduction in the size of the cystic cavity was assessed by radiologic follow-up every 4 months. The optimal time for cystectomy and removal of the drainage tube was determined from the radiologic re- ductiqn in the cystic lumen.

All patients were seen annually for a clinical and radiologic follow-up after the first reexamination 9 months after the cystectomy. All data were comput- erized.

RESULTS

Forssell group Ia comprised 27 patients (14 male); group Ib was not represented in the material. Forssell group II included five patients (three male); group III

Fig. 7. Orthopantogram of 21-year-old man showing OKC in left angular and ramus regions.

contained one female, whereas group IV included three patients (one male); and group V comprised eight patients (four male). The distribution of OKCs according to age and sex is shown in Fig. 4; Fig. 5 shows the distribution according to sex and Forssell group.

Recurrence of OKC occurred in 8 of the 32 patients treated with primary cystectomy (two men in the age group 40 to 49 years, and six females, one aged 15 years, two from the age group 40 to 49 years, and three from the age group 50 to 59 years). Recurrence occurred only in Forssell group Ia (i.e., the group with thin parakeratotic cyst epithelium with palisade-like basal cells).

Of a total of 54 OKCs, 44 (82%) were found in the mandible, of which 27 were in the ramus and angular regions (61%) and 17 in the mandibular body (39%). Ten OKCs (18%) were seen in the upper jaw, of which seven were in the frontal and canine regions (70%), and three in the molar region (30%).

All eight recurrences were observed in the mandi- ble (seven in the angular and ramus regions and one in the premolar region). Seven of the eight recur- rences were solitary, and one multiple; three were

ORAL SURG ORAL MED ORAL PATHOL September 199 1

Fig. 8. Orthopantogram of same patient 10 months after insertion of drainage tube, revealing marked reduction in cystic lumen.

Fig. 10. Biopsy in connection with cystectomy and re- moval of tube 10 months after biopsy in Fig. 9, demonstrat- ing considerable change in histologic features. Cyst could not longer be classified as Forssell group Ia.

Fig. 9. Biopsy in connection with cystotomy and drain- age of OKC shown in Fig. 5, displaying OKC Forssell group Ia.

unilobular and five multilobular. Of all 44 cases of OKC, 37 were solitary and 7 were multiple, and 26 were unilobular and 18 multilobular. The maximum radiographic diameter was 15 mm in one case (pre- molar region), 20 to 49 mm in three cases, and more than 50 mm in four cases. In six of seven cases of re- currence in the lower third molar region, the ramus and/or the body of the mandible were involved at pri- mary cystectomy. Osseous perforation on the lingual side of the ramus was present in four cases, adhesions to the content of the mandibular canal in three, and adhesions to soft tissue in three others. Biopsies taken from patients with recurrence showed no histologic alteration in six cases, whereas two cases recurred as Forssell group IV and group V, respectively. Recur- rence was observed in seven patients during the first 2 years of observation and in one patient after 5 years. Three patients were subjected to reoperation twice; two of these had involvement of the mandibular canal and persistent postoperative paresthesia of the lower lip developed.

A polyethylene drainage tube was inserted after

biopsy, according to the method of Nielsen15 (Fig. 6) in 12 cases; primary cystectomy was performed on these patients only after radiographic reduction in the cystic lumen (Figs. 7 and 8). No recurrence was seen in these 12 patients during an observation period of between 7 and 17 years. In the cases shown in Figs. 7 and 8, the cystic epithelium had undergone pro- nounced histologic change (Figs. 9 and 10). The de- compression took 1 to 14 months (mean 10 months), and the largest diameter of the cystic lumen was more than 50 mm in five cases and between 15 and 45 mm (mean 40 mm) in the remaining seven at the time when the drainage tube was inserted. Biopsy of the cystotomy material showed nine cases of Forssell group Ia, and one in each of groups II, IV, and V. Forssell group Ia was not found in the cystectomy material. In four of the nine cases of Forssell group Ia at cystectomy, the cystectomy material could no longer be classified as OKC.

Cysts with rapid increase in size showed a corre- sponding rapid reduction in the cystic lumen after drainage. However, the actual reduction in the lumi- nal diameter did not occur as rapidly as that demon- strated by radiography.

It is noteworthy that the patients had little incon- venience from the tube, and none had difficulty in the routine flushing. Therefore cystectomy and removal of the tube could wait until considerable radiographic reduction in the size of the cyst had occurred.

Forty-three of the patients were followed for 7 to 19 years (mean 9 years). One patient was followed for only 22 months before moving from the catchment area.

DISCUSSION

In the present investigation agreement was good with other studies with respect to age; most studies

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have shown a marked prevalence of OKC in the age groups 20 to 29, and 40 to 59 years. There is also agreement as to the frequent localization of the OKC to the angular and ramus regions of the mandible.* I, I3

The sex ratio in the current investigation differed somewhat from that reported in other studies, all of which have shown a slight male predomi- nance 4-6,9-l 1, 13

It is remarkable that all the recurrences occurred in cysts with parakeratotic thin bandlike epithelium with palisade-like basal cells (Forssell group Ia) and that all were located in the mandible (seven in the an- gular and ramus regions and one in the premolar re- gion). It is also remarkable that the recurrences occurred three times as often in women as in men (fe- male/male ratio 6:2).

The frequency of recurrence in 27 OKC cysts with parakeratotic, thin, bandlike epithelium with pali- sade-like basal cells was 30% (8/27), whereas the rate in the whole material was only 18% (8/44).

As in other studies, we found that the recurrence of OKC is most likely to occur in cases requiring com- plicated surgery (i.e., in those cases where the OKC is situated in the angular and ramus regions with in- volvement of the mandibular canal and/or with adhesions to soft tissue through osseous perforation).

The change in the histologic features of the cystic epithelium after the insertion of a drainage tube is similar to that occurring after inflammation.16

The increased epithelial depth observed after de- compression facilitated cystectomy, especially when the latter was performed after a marked reduction in the cystic lumen. The reduction in the size of the cyst resulted in achieving a safe distance to the mandibu- lar canal or other previously involved structures. Thus postoperative complications were avoided without difficulty. Finally, the tendency toward recurrence was reduced or even eliminated entirely, because it was often possible to remove the cyst in toto.i3

CONCLUSION

The recurrence of OKC is most likely to occur in parakeratotic OKCs with thin, bandlike epithelium with palisade-like basal cells (Forssell group Ia). The use of a polyethylene drain inserted at cystotomy and biopsy in larger cysts of various types gave a number of advantages to the surgeon and few inconveniences to the patient.

1. The diagnosis of OKC (with particular refer- ence to Forssell group Ia) versus non-OKC can be established by means of cystotomy or biopsy.

2. The procedure is advantageous for the patient, because the treatment can be carried out in two sessions of minor surgery with the patient under local anesthesia. For the surgeon the method simplifies the surgical procedure of removing

Keratocyst recurrence and decompression 269

3.

solid coherent cystic tissue with no adhesions from a minor cavity, instead of removing cob- weblike, fragile cystic tissue with adhesions to adjoining structures in a cavity with difficult ac- cess and entailing the risk of damage to adjoin- ing structures and the possibility of spontaneous fracture of the jaw. Decompression of larger cysts appears to reduce the tendency to recurrence of OKC.

We thank the staff of the Department of Oral Surgery and Oral Medicine, as well of the Department of Pathology, Odense University Hospital, for help and advice; we also thank Lise Hansen, MSc, Funen County Medical Comput- ing Department, Odense University Hospital, for the data processing.

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Reprint requests: N. Brdndum, DDS, DOS Department of Oral Surgery and Oral Medicine Odense University Hospital DK-5000 Odense C, Denmark