LARGE OSTEOMA OF THE F R O N T A L SINUS

A METHOD OF REMOVAL TO MINIMISE SCARRING AND PREVENT DEFORMITY

By THOMAS GIBSON, M.B., F.R.C.S.Ed. From the Department of Plastic Surgery, Ballochmyle Hospital

and

FORBES M. WALKER, M.B., Ch.B., F.R.F.P.S. From the Ear, Nose, and Throat Service, Ayrshire

OSTEOMATA of the frontal sinus are uncommon but by no means rare. Teed (I94I), in an exhaustive review of the literature, collected 321 cases, and since then several authors have reported other cases either singly or in groups; Conley (1944) reported one case ; Dowling (1945) five cases ; Novick (1947) one case; Brunner and Spiesman (I948) four cases ; Vadala and Somers (1949) six cases ; King (I95O) five cases. Hallberg and Begley (I95O), from the records of the Mayo Clinic since 193o, found forty cases in all.

With the exception of one case recorded by Hallberg and Begley (i95o), in which sarcomatous change was revealed histologically after removal, all the osteomata recorded were benign growths. They consist mainly of compact bone with a varying amount of spongy bone often arranged as a central core. In the early stages most are sessile, but as they grow they become pedunculated with, often, a very narrow neck. They may arise from any part of the wall of the sinus.

Clinically they fall into two main groups : first, the symptomless and usually small tumours which are detected accidentally on radiological examination, and secondly, those which are already causing symptoms. Undoubtedly some of the first group are early stages of slowly growing tumours which will eventually produce symptoms, but Brunner and Spiesman (1948) stress the fact that some of the smaller tumours grow very slowly if at all (one of their cases, followed for six years, showed no change whatever in size), and they believe that these are probably exostoses and not true tumours. Evidence of the rate of growth is scanty, but most writers consider it slow but inexorable. Hallberg and Begley (I95O), in one case, noted an increase in size of only 30 per cent. in nine years. Thomas (I918), however, recorded a patient in whom, nine months after inadequate removal, an osteoma had regrown to a size greater than the original.

As they grow a variety of effects may be produced by expansion of the tumour. At a comparatively early stage, when the lesion is in the lower part of the sinus, the fronto-nasal duct may be blocked with a resultant mucocoele or pyoc~ele. Expansion towards the orbit may cause exophthalmos, ptosis, or diplopia, depending on which sector is encroached upon. Erosion of the anterior plate gives rise to an external swelling, while erosion of the posterior plate may cause intracranial complications, pneumo-encephalocoele, brain abscess, and meningitis all having been reported.

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LARGE OSTEOMA OF THE FRONTAL SINUS 21I

Diagnosis follows automatically on X-ray examination of the skull since the appearances are quite typical. It should be noted, however, that with a large osteoma filling the sinus radiology may fail to give one desirable piece of informa- tion, namely, the site of origin of the growth. This was illustrated in the present case (Figs. 2 and 3)- In such circumstances one must be prepared to find that the osteoma arises from the posterior plate and that its removal causes a tear of dura mater. Intracranial complications following dural tears were the main cause of the high mortality in the early cases (Teed, I94I). To-day, however, prompt repair of the tear with fascial or muscle graft and antibiotic therapy (Conley, z944) have minimised this risk.

When the tumour is producing pressure effects, or repeated radiographs show a steady growth, operative removal is indicated. The various approaches which have been used were recently reviewed by Vadala and Somers (i 949). The Killian incision gives inadequate exposure unless for very small tumours, and what has irrpressed us most is that, with the exception of the butterfly incision through both eye- brows, most authors have used an approach involving either transverse or vertical incisions through the forehead which tend to leave a marked scar as many of the post-operative photographs show. A coronal incision behind the hair line has been used, but only for the transcranial approach of Cushing (I927), and Dowling (I945) considered this incision too radical for anterior exposure.

Scant attention, too, has been paid to Fro. the bony deformity which results from the Pre-operat ive photograph showing fullness

in left upper eyelid. ablation of sufficient of the anterior plate to permit the removal of the larger osteomata. With the exceptiofi of Conley (r944), who used a tantalum plate at a secondary operation to replace the bone lost, we have found no record of any attempt to prevent or correct this deformity.

When we were first presented with the case to be described, one important consideration was the prevention of an obvious forehead scar and a bony deformity. A coronal incision just behind the hair line seemed the obvious choice, since the scar would be hiddefi and the inverted flap would give excellent exposure. Our first idea was to prepare the frontal bone, after removing the tumour, for an acrylic plate to be inserted at a later date. Previous experience, however, of such inert plates as a replacement of the anterior sinus wall has shown them to be unsatisfactory. It is impossible to make the plate fill the whole bony cavity completely. A dead space remains, and this, of course, being in contact with the nasal cavity, makes infection around the plate liable to occur at any time.

It was finally decided to turn down the forehead flap only as far as the upper border of the frontal sinus, to chisel through the anterior plate along its extreme upper and lateral borders, and then to attempt to fracture downwards the anterior plate still firmly attached to the forehead flap. This would preserve the blood

FIGS. 2 and 3 Pre-operative X-ray photographs showing the osteoma in situ. The erosion and expansion of the supra-orbital ridge account

for most of the external swelling.

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L A R G E O S T E O M A OF THE F R O N T A L S I N U S 2I 3

supply tO the plate, so that it could be replaced with the flap and re-establish bony contour after removal o f the osteoma. T h e ease with which this manoeuvre was carried out, the completeness of the exposure gained, and the absence of any post-operative deformity are the main reasons for publishing this report.

CASE REPORT

History.--In April 195o the patient first noticed that his left eyelids were puffy and that his left eye watered when out of doors. At first treated with eye-drops, he was later referred to an ophthalmic clinic in October 195 ° where lavage of the tear duct was carried out on several occasions with little improvement. The condition suddenly became much worse in January 1951, when the left eye was almost closed and there was

FIG. 4 Diagram to show how the forehead flap is freed laterally to the supra-orbital ridges but medially only to the borders of the frontal sinus. A small osteotome is used to cut round the margins of

the anterior wall.

FIG. 5 The upper and lateral margins of the anterior wall have been cut and the anterior plate frac- tured downwards, still firmly attached to the

forehead flap.

tenderness in the left supra-orbital region. An X-ray film of his skull revealed a large osteoma completely filling the left frontal sinus and extending well into the right (Fig. 2) and he was referred to the E.N.T. clinic where he was seen by one of us (F. M. W.). It was realised that the removal of the tumour was as much a plastic as an E.N.T. problem, and he was admitted to Ballochmyle Hospital on 2oth February 1951 for a combined operation.

Clinical Findings (2oth February I95I ) . - -The acute phase had settled completely and the only external evidence of the tumour was slight swelling and ptosis of the left upper eyelid (Fig. I). No pus was seen in the nose or the nasopharynx, although there was a definite increase in the congestion of the mucosa of the left nostril. An old marginal perforation of the right drum was present.

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Operation (22rid February I95I ) . - -Endot rachea l gas and oxygen anmsthesia was used and the pat ient ' s head raised slightly on a sand-pillow. A coronal incision I can.

Centi~etres. - : FIG. 6

The osteoma viewed from above to show the small anterior pedicle.

FIG. 7 The osteoma from behind.

behind the hair line was made extending downwards on each side to the level o f the supra-orbi tal ridge. The forehead flap was carefully s t r ipped downwards from the pericranium. Laterally the dissection proceeded until both supra-orbital ridges were

LARGE OSTEOMA OF THE FRONTAL SINUS 215

exposed. Centrally it was carried only to what we judged to be the upper and lateral borders of the sinus (Fig. 4). This was decided upon by frequent reference to the X-rays, and assessing the position of the sinus relative to the supra-orbital ridges, the root of the nose, and the globella. At the central point of the estimated upper border a small, sharp osteotome was driven gently through the bone. This proved to be in the correct spot, as the point of the instrument could be slipped between the osteoma and the roof of the sinus. The cut was enlarged laterally and it was then found possible to " spring " the anterior plate outwards slightly and so visualise to some extent the exact limits of the sinus. When the plate had been chiselled along its entire upper margin and downwards as far as the supra-orbital ridge on both sides, a flat-bladed instrument--a metal ruler-- was inserted under the plate. A sharp wrench fractured the lower attachment, which was already weakened because of the erosion of the orbital ridges, and the osteoplastic flap was turned down completely, exposing the whole of the sinus with the osteoma in situ (Fig. 5). Some thick green pus was present, lodged between the upper surface of the tumour and the superior margin of the left frontal sinus. The tumour was entirely covered with mucous membrane and appeared to be contained completely in the left sinus, although this was greatly expanded and in places the septal wall was deficient. The right sinus was repre- sented only by a small loculus which can be seen in the X-ray photograph.

Rocking the turnout showed it to be attached not to the posterior wall as we had feared but to the region of the root of the nose. I t fractured easily and was removed, carrying with it a small area, about I cm. in diameter, of the anterior plate (Figs. 6 and 7). Toilet of both sinuses followed, with removal of the mucosa, but as suggested by Dowling (I945), and in view of the cases of stenosis of the duct which have followed interference (cf. Vadala and Somers, I949), the fronto-nasal ducts were left alone, no attempt being made to provide extra FIG. 8 drainage. The flap was then replaced and the Post-operative photograph showing anterior plate, which was noted to be bleeding absence of scarring and bony deformity. normally and which had " cracked" through the The slight residual fullness in the left

upper eyelid is due to the underlying midline on being turned down, was tacked into place bony expansion. with a few catgut sutures through the pericranium.

The wound was closed with dependent drainage on both sides. To avoid any external pressure forcing the anterior plate into the sinus, a small plaster slab was made and moulded gently over the forehead. A firm bandage was then applied. Penicillin in dosage of 600,000 units per day was administered for six days.

Apart from a small hmmatoma under the scalp which was evacuated when the drains were removed on the second day, convalescence was uneventful. Most of the stitches were removed on the sixth day and the remainder on the eighth. One week later the patient was allowed home, the P.O.P. splint having been replaced with a lighter slab of " Glassoma." The splint was kept in place until the fourth week post-operatively when it was felt that no further protection should be necessary. X-rays at this time showed that the anterior plate was in good position and no external deformity was noticeable.

The patient was last seen three months after operation. There has been no change in the position of the anterior plate (Fig. 9) and no complications have developed. The swelling in the upper left eyebrow is still present but gradually diminishing (Fig. 8).

216 BRITISH JOURNAL OF PLASTIC SURGERY

FIGS. 9 and IO Post-operative X-ray photographs.

LARGE OSTEOMA OF THE FRONTAL SINUS 217

Pathological Examination of the Tumour (Dr Russell Da l l achy) . - -The microscopic appearances of portions taken from the pedicle are those of a simple osteoma of compact or eburnated type. Irregularly contoured and greatly thickened trabeculm of mature bone, devoid of Haversian systems, enclose relatively small amounts of fine vascular fibrous tissue. A few small circular spaces in the compact bone trabeculm each contain a small blood-vessel. The large irregular spaces between the compact trabecul~e are filled with a fine, loose, moderately cellular fibrous tissue network ; in this network there are numerous thin-walled, poorly supported blood-vessels of variable diameter. There is no evidence of infection or malignant change.

COMMENT

In addition to the absence of post-operative deformity, this approach has the advantage of providing the widest possible exposure of the frontal sinus. Not only does this allow of easy removal of the tumour and toilet of the sinus, but it gives excellent access to the posterior wall should the turnout prove to originate there and any dural tear result from removal. The presence of a well-marked bony septum between the two sinuses should not prove to be any great difficulty. In this case we were prepared to divide it with an osteotome, but it appeared to have been eroded through, and this was not necessary. Should the tumour be confined within one sinus only, the osteoplastic flap could be limited to the anterior wall of that sinus, or if it were desired to inspect both sinuses the septum could easily be cut from above with a sharp osteotome.

NOTE.- -As frequently happens with unusual cases, a second patient with a large osteoma of the frontal sinus was seen shortly after this article had been sent for publication. The same operative procedure was used, and this second experience of the method confirms in all respects our opinion of its usefulness in this type of case. The osteoma was even larger than that described above, and was extremely soft and vascular. Section shows a histological picture of fibrous dysplasia of bone.

Our thanks are due to Mr J. Scott Tough, Surgeon in Charge of the Plastic Unit at Ballochmyle, for his permission to publish this case, and to Dr Russell Dallachy for the histological examination.

REFERENCES

BI~tIN~IER, H., and SPIESMAN, I. G. (1948). Ann. Otol., etc., St Louis, 57, 714. CONLEY, J. J. (1944)- Arch. Otolaryng., 4 o, 295. CUSHING, H. (1927). Surg. Gynec. Obstet., 44, 721. DOWLING, J. R. (I945). Arch. Otolaryng., 4~, 99. HALLBERG, O. E., and BEGLEY, J. W., Jun. (195o). Arch. Otolaryng., 5x, 75o. KING, N. E. (195o). Arch. Otolaryng., 5x, 316. NOVlCK, J. N. (1947). Arch. Otolaryng., 46, 655. TEED, R. W. (1941). Arch. Otolaryng., 33,255. THOMAS, G. F. (1918). Amer..7. Roentgen., 5, 341. (Quoted by Teed, 1941.) VADALA, A. J., and SOMERS, K. (1949). Arch. Otolaryng., 5 o, 618.