Sir,

We thank Dr McNab1 for his comments on our report of isolated eyelid edema in Melkersson–Rosenthal Syndrome (MRS).2 He suggests that our cases are better considered examples of acne rosacea, and cites his own study3 and the case report of Lai et al4 in support of this.

In Dr McNab's case series, histopathological examination of eyelid skin from five patients with a clinical diagnosis of acne rosacea and chronic eyelid edema showed some degree of granulomatous inflammation in three specimens.3 The granulomas were not illustrated but were described as ‘poorly formed’ (case 4), ‘single’ (case 11) and ‘surrounding dilated lymphatics’ (case 15). Lai et al4 also referred to the presence of ‘ill-defined perivascular granulomas’ but did not illustrate them. Other studies of chronic eyelid edema in rosacea did not mention dermal granulomas.5, 6 In none of our cases was rosacea felt to be the primary underlying cause, either clinically or histopathologically.

In our practice, we do not regard poorly defined granulomas as indicative of any specific diagnosis. Granulomatous rosacea is typically characterised by a tuberculoid (necrotising) or sarcoid-like response, possibly to the contents of hair follicles. In our series, the granulomas were neither tuberculoid nor sarcoid-like but were sharply defined, perivascular, and perilymphatic, often with an intralymphatic component. In addition, and illustrated in our paper, discrete granulomas were identified in orbicularis muscle and anterior orbital soft tissue, which does not appear to have been described in rosacea.

Dr McNab may be correct in saying that MRS is over diagnosed in cases of isolated eyelid edema.1 Nevertheless, the clinico-pathological pattern that we and other authors have ascribed to monosymptomatic MRS appears quite distinct. Until our understanding of the etiology and pathogenesis of oro-facial granulomatosis, of which MRS is one part, increases, we see no justification for regarding these cases as a form of granulomatous rosacea.