Sphenoid sinus mucocele: A rare complication of transsphenoidal hypophysectomy. (Original Article).

Abstract

Only seven cases of a sphenoid mucocele occurring after transsphenoidal hypophysectomy have been previously reported in the world literature. In this article, we report a new case, which occurred in a 67-year-old man. The sphenoid sinus mucocele developed 12 years following transsphenoidal hypophysectomy and adjunctive radiotherapy. The patient was successfully managed with incision and drainage. Although transsphenoidal hypophysectomy is a common operation, this particular complication appears to be rare or at least under-reported. Sphenoid sinus mucocele deserves consideration in the differential diagnosis of a sphenoidal parasellar mass in a patient who has undergone an earlier transsphenoidal hypophysectomy.

Introduction

Paranasal sinus mucoceles are the result of outflow obstruction and secondary filling of the involved sinus. Left unchecked, the mucocele will apply pressure to adjacent structures and interfere with their function. This pathophysiology is particularly important in the case of sphenoid sinus mucoceles, where several critical neurologic and vascular structures are so closely related. The delayed occurrence of symptoms related to these structures is of particular importance in patients who have a history of transsphenoidal hypophysectomy, because they might be associated with a recurrence of hypophyseal neoplasms. Nevertheless, there have been few reports of sphenoid mucocele following transsphenoidal hypophysectomy. In this article, we report a new case.

Case report

A 67-year-old man underwent an uneventful transsphenoidal hypophysectomy for pituitary adenoma with suprasellar extension in 1985. There were no immediate postoperative complications, and the patient subsequently underwent adjunctive radiation therapy. In 1997, he developed cavernous sinus syndrome on the right. The patient's chief complaint was the same as it was in 1985: several months of diplopia. He also noted right midface numbness. He denied headaches or weakness.

Examination revealed right-sided ptosis and a mild right oculomotor (III) and trochlear (IV) nerve palsy that was most noticeable on medial gaze. The pupils were equal in size and reactive to light. Hypoesthesia to pinprick was noted in the distribution of the right maxillary division of the trigeminal (V2) cranial nerve. The remainder of the examination was unremarkable.

T1-weighted magnetic resonance imaging (MRI) revealed a dense homogenous lesion that measured 3 cm. The lesion occupied the sphenoid sinus and sella turcica and extended into the cavernous sinus on the right (figure).

With his symptoms progressing, the patient underwent operative exploration via a transseptal approach to the sphenoid sinus. A green-brown lesion was seen toward the right. The lesion was perforated with a needle, which yielded a thick, yellow-green material. The lesion was widely opened with a knife, which revealed a large cystic cavity; the cavity was irrigated. Histologic examination of a cyst wall biopsy specimen identified fibrous tissue with chronic inflammation and a focus of ciliated epithelium consistent with a mucocele.

The postoperative period was uncomplicated, and the cavernous sinus syndrome partially resolved.

Discussion

Until now, only seven cases of a sphenoid mucocele occurring after transsphenoidal hypophysectomy had been reported in the world literature. (1-3) Given that previous surgery is a known risk factor for paranasal sinus mucoceles and given the number of transsphenoidal hypophysectomies that have been performed, it is surprising that this condition is so rarely reported.

Although a single case does not prove the etiologic pathophysiology that is involved in this condition, the preceding transsphenoidal hypophysectomy and subsequent radiation therapy likely played a significant role in the mucocele development in our patient.

Our case is somewhat unusual in that headache was not a feature. Nugent et al reviewed 63 reported cases of sphenoid mucocele and determined that headache was the most common symptom, occurring in 71% of patients. (4) The second most common complaint is visual disturbance. Failing vision is usually gradual and not complete. The most common ophthalmoplegias are caused by oculomotor (III) and trochlear (IV) nerve palsies; abducens (VI) palsies are the least common. Other less frequently encountered findings include trigeminal nerve hypoesthesia and pituitary insufficiency.

Computed tomography of a sphenoid mucocele usually shows a cystic mass that appears to be well encapsulated and does not enhance. The mass not only occupies the sphenoid sinus, it invades the adjacent structures, as well. (5) MRI reveals a similar pattern. The T1 and T2 signal intensities of the actual mucocele are variable. (6)

In a condition as rarely reported as sphenoid mucocele following transsphenoidal hypophysectomy, a broad differential diagnosis is required. Skull base malignancy must be considered, particularly in patients who have a history of pituitary neoplasms. Possible malignancies include craniopharyngioma, meningioma, chordoma, glioma, meningoencephalocele, nasopharyngeal tumor, sphenoid sinus tumor, internal carotid artery aneurysm, sphenoid osteoma, cholesteatoma, and fibrous dysplasia.

Treatment for paranasal sinus mucoceles ranges from incision and drainage to total excision of the cyst. (5) Access to the sphenoid sinus can be achieved by several routes. Craniotomies are very rarely required, and they are associated with more frequent and more serious complications. (4) The sphenoid can be approached by transseptal routes or by using endoscopic techniques. Treatment is usually successful. (4)

From the Department of Pediatric Otolaryngology, Allegheny General Hospital, Pittsburgh (Dr. Buchinsky); the Department of Neurosurgery, Medical College of Wisconsin, Milwaukee (Dr. Gennarelli); the Department of Otolaryngology, Mayo Clinic, Rochester, Minn. (Dr. Strome); the Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston (Dr. Deschler); and the Department of Otolaryngology--Head and Neck Surgery, Hahnemann University, Philadelphia (Dr. Hayden).

References

(1.) Kessler L, Legaludec V, Dietemann JL, et al. Sphenoidal sinus mucocele after transsphenoidal surgery for acromegaly. Neurosurg Rev 1999;22:222-5.

(2.) Herman P, Lot G. Guichard JP, et al. Mucocele of the sphenoid sinus: A late complication of transsphenoidal pituitary surgery. Ann Otol Rhinol Laryngol 1998;107:765-8.

(3.) Schoen D. [Mucocele of the sphenoid bone following hypophysectomy]. Fortschr Geb Rontgenstr Nuklearmed 1970;11:114-6.

(4.) Nugent GR, Sprinkle P, Bloor BM. Sphenoid sinus mucoceles. J Neurosurg 1970;32:443-51.

(5.) Saito Y, Hasegawa M, Hiratsuka H, Kern EB. Computed tomography in the diagnosis of mucoceles of sphenoid and ethmoid sinuses. Rhinology 1980;18:51-5.

(6.) Ruelle A, Pisani R, Andrioli G. "Unusual" MRI appearance of sphenoid sinus mucocele. Neuroradiology 1991;33:352-3.