Familial reactive perforating collagenosis: a clinical, histopathological study of 10 cases

To study the clinical and histopathological features of familial reactive perforating collagenosis (RPC).

Ten patients, including affected siblings in three, took part in the study. Parental consanguinity was present in one. Histopathological study was performed in all patients.

The eruptions appeared mainly during infancy or early childhood as papules showing a central plug, which subsided within 10 weeks. Areas commonly affected were the face, extremities and trunk. Rare sites were the scalp, ears and buttocks. One pregnant woman, in whom RPC had first manifested around puberty, had relatively widespread lesions. In those with seasonal variation, recurrences were seen a little more frequently in summer than in winter owing to the longer duration of the former. Histopathology confirmed the diagnosis with follicular involvement in four cases. In two patients whose backs were also affected, the lesions went unnoticed, as they were small and inconspicuous. In addition, the brother of a girl with RPC who claimed to be free of the dermatosis, had facial scars suggestive of RPC in the past.

Familial RPC can remain quiescent for a long period and the inherited defect not only shows extreme variability in expression but also demonstrates that lesions can be few and localized so as to escape notice in individuals and family members presenting with this benign, uncommon and self-subsiding dermatosis. In all patients topical retinoic acid was helpful in early regression. Sunscreens may mitigate the severity of RPC in those whose lesions are precipitated in summer but this needs further evaluation.