A kindred with familial progressive hyperpigmentation-like disorder: Implication of fibroblast-derived growth factors in pigmentation

Two patients with a generalized, progressive dyschromatosis disorder are described and investigated as a model to study the role of fibroblast-derived mediators on skin pigmentation. The patients (father and daughter) had had a widespread hyperpigmentation since early life which then progressively worsened with the appearance of hyperpigmented macules, café-au-lait macules and freckles, also involving the lips, palms and soles, intermixed with small hypopigmented spots. These features resembled those of familial progressive hyperpigmentation (FPH). Histology revealed a normal epidermis with pronounced keratinocyte hyperpigmentation and the presence of dermal melanophages. Ultrastructural analysis showed basal and suprabasal keratinocytes enriched in melanosome complexes. Immunohistochemical staining displayed an increased expression of hepatocyte growth factor (HGF), stem cell factor (SCF) and keratinocyte growth factor (KGF) in fibroblast-like cells of the upper dermis in hyperpigmented lesions of both patients, compared to control healthy skin. Our data suggest that a persistent activation of fibroblasts abnormally stimulating melanocyte functions is involved in hyperpigmentation disorders.