Short foot length: a diagnostic pointer for harlequin ichthyosis

Among the fetal skin disorders, harlequin ichthyosis is the one that has specific sonographic features in the antenatal period. A few cases of antenatal diagnosis of harlequin ichthyosis with typical facial features of ectropion and eclabium have been described. The manifestation of the phenotype is usually in the third trimester. Fetal skin biopsy can be done in the late second trimester for diagnosing fetal skin disorders. We aimed to see whether a short foot length could be a pointer for the diagnosis of harlequin ichthyosis in the second trimester before the full phenotypic manifestation, which is usually seen in the third trimester.

We report 3 cases of harlequin ichthyosis, 2 of them diagnosed in the third trimester with abnormal facial features and another second-trimester sonographic diagnosis based on short foot length, without eclabium and ectropion.

In all 3 cases, the foot length was considerably smaller than the femur length, especially in the third case, in which the foot length was smaller than the femur length before the manifestation of the typical features of harlequin ichthyosis.

Fetal foot length may be an important and probably the first marker seen in the second trimester for the diagnosis of harlequin ichthyosis.