Horner's syndrome

Horner's syndrome consists of the classic clinical manifestations of miosis, partial ptosis, and apparent enophthalmos and is occasionally accompanied by anhidrosis and pain. The pupil is variably miotic, depending on the location, completeness, and chronicity of the deficit. Horner's syndrome may occur with a lesion anywhere along the oculosympathetic pathway.[1]

Thymic cysts are uncommon lesions derived from the thymopharyngeal duct. They usually are found in asymptomatic adults, although cardiac compression due to extrinsic pressure or rupture in the pericardial space and chest pain secondary to intracystic infection have been reported.[2-4]

We report a patient suffering from Horner's syndrome due to a cystic tumor of the thymus growing from the upper portion of the mediastinum into the neck. Horner's syndrome was due to extrinsic compression of the sympathetic plexus that accompanies the carotid. To our knowledge, there are no previous descriptions of thymic cysts leading to Horner's syndrome.

Case Report

A 64-year-old man was discovered by chance to have Horner's syndrome in January 1990. The patient did not remember when the onset of ptosis occurred. He was asymptomatic and had no previous history of migraine. On physical examination, the only positive findings were ptosis on the right and the fact that the right pupil was 2 mm smaller than the left. there was no evidence of anhidrosis or enophthalmos. Elemental blood analysis, an electrocardiographic study, and thyroid function test results were normal. Chest radiographs revealed superior mediastinal enlargement. Computed tomography of the thoracic inlet and neck revealed a large (12 cm in diameter), low-density mass, which deviated the right carotid artery to the right and the trachea to the left (Fig 1).

At surgery, the tumor was found to contain clear fluid and was completely excised via a cervical incision. Microscopic study disclosed a fibrotic membranous wall with thymic tissue (Fig 2) with no evidence of malignancy.

The patient recovered from surgery and six months later remained asymptomatic. On physical examination, ptosis had disappeared, and anisocoria was less evident than it had been initially.

Discussion

Horner's syndrome may occur with a lesion anywhere along the sympathetic pathway, but it usually results from cervical sympathetic chain compression by a malignant tumor. With a lesion of the brain stem or cervical spinal cord, other signs of neurologic dysfunction usually predominate. Second-order preganglionic involvement may occur with lesions of the superior mediastinum, the apex of the lung, or the neck, whereas postganglionic involvement may be the result of an abnormality of the internal carotid artery, a lesion in the middle cranial fossa or cavernous sinus, or a migraine equivalent.[1,5]

Thymic cysts may occur at any anatomic level, from near the base of the neck to the diaphragm. Although distant or discontinuous accessory lobes commonly occur within the anterior mediastinal and cervical regions, thymic cysts are often found near the base of the heart.[6,7] Thymomas often undergo cystic degeneration, at times so extensive as to result in a gross picture similar to that of a thymic cyst. Radiography does not allow distinction between benign thymic cysts and other potentially malignant lesions.[8] However, careful histologic examination of the cyst will invariably disclose residual tissue in its wall.[2] Thymic cysts should, therefore, be excised, principally to differentiate them from thymomas.

We believe that the most important clue to diagnosis of thymic cysts as the cause of Horner's syndrome is the clinical history. Thus, diagnosis may be suspected in asymptomatic subjects with mediastinal enlargement in whom Horner's syndrome is not accompanied by other neurologic signs or symptoms.

References

[1] Slamovits TL, Glaser JL. the pupils and accommodation. In: Duane TD, Jaeger EA, eds. Clinical ophthalmology (vol 2). Philadelphia: Lippincott, 1988; 1-26 [2] Jones KW, Pietra GG, Sabiston DC. Primary neoplasms and cysts of the mediastinum. In: Fishman AP, ed. Pulmonary diseases and disorders. New York: McGraw-Hill, 1980, 1490-521 [3] Smith SB. Thymus In: Anderson WAD, Kissane JM, eds. Pathology (vol 2), 7th ed. St Louis: CV Mosby, 1977; 1575-600 [4] San Millan J, Roldan Sanchez JR, Nunez V, Bogaert M, Larru E. Clinical and radiological aspects of mediastinal thymic cysts. Arch Bronchopneumol 1989; 25:314-17 [5] Beck RW. Disorders of the eye, visual system and oculomotor system. In: Kelley, ed. Textbook of internal medicine. Philadelphia: Lippincott, 1989; 464:2366-369 [6] Day DL, Gedgandas E. the thymus. Radiol Clin North Am 1984; 22:519-38 [7] Baron RL, Lee JK, Sagel SS, Levitt RG. Computed tomography of the abnormal thymus. Radiology 1982; 142:127-34 [8] Dunne MG, Weksberg AP. Thymic cyst: computed tomography and ultrasound correlation. CT 1983; 7:351-55

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