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Editor,—George et al 1recently undertook a review of 23 cases of Horner’s syndrome presenting in the first year of life. They remind us of the difficulty in differentiating between congenital and acquired Horner’s syndrome in this age group. In their introduction they state that, in both congenital and acquired cases, “heterochromia may appear to be progressive as the child develops normal pigmentation in the fellow iris”. Iris heterochromia would therefore appear to be of little value in distinguishing between congenital and acquired cases, the latter potentially being the group with underlying pathology. The authors conclude with a management protocol for the investigation of Horner’s syndrome in infancy—namely, a full general examination and urinary vanillylmandelic acid levels.
However, their inclusion of the recommendation that further investigation is indicated if increasing iris heterochromia is noted would appear to be contradictory to their earlier statement. Iris pigmentation depends predominantly on the distribution of pigment within melanocytic cells on the anterior border and within the stroma. These cells migrate into the human iris late in gestation and postnatally, modulated by the sympathetic nervous system.2In 1915, Sym3 noted that iris colour is not fully developed until the 12th to 16th month, an observation continued by Giles et al 4 in 1958 who reported the development of normal iris pigmentation in children up to 2 years of age. Thus, patients with Horner’s syndrome, either congenital or acquired in the first year of life, might be noted to have progressive heterochromia as the fellow eye pigments. On this advice, both groups of children would be subject to further investigation which the authors are suggesting we should try to avoid.
In order to further clarify this excellent protocol, we would suggest the omission of progressive iris pigmentation among the list of signs meriting radiological investigation.
Editor,—Thank you for the interest shown in our paper. We agree that in a congenital Horner’s syndrome, an apparent increase in iris heterochromia may be observed as a result of an increase in the iris melanocyte pigment of the unaffected eye during the first 18 months of life. However, progressive heterochromia has been reported following acquired Horner’s syndrome in both children and adults. In our patient with progressive heterochromia a Horner’s syndrome had been diagnosed in infancy. When she presented to us the child’s mother was concerned that the affected eye had originally had some pigment but was becoming progressively depigmented. A computed tomograph of the thorax was subsequently performed and showed a ganglioneuroma. We have therefore included increasing heterochromia in our series as an index of suspicion because this had prompted further investigation in this one patient.