Idiopathic guttate hypomelanosis. Ultrastructural study

Abstract

Idiopathic guattate hypomelanosis (IGH) has been studied histochemically (split-dopa) and ultrastructurally in three patients. Affected skin was compared to normal surrounding skin. Argentic stains revealed a decrease in the melanin content of affected epidemis and pigment granules were irregularly distributed. Split-dopa preparations showed a decrease in the the number of dopa-positive melanocytes in hypomelanotic macules. Most of the melanocytes were rounded in from and either lacked dendrites or had fragmented ones. Ultrastructural study confirmed the progressive loss of epidermal melanocytes in skin affected by IGH and revealed two types of melanocytes, healthy melanocytes with normal melanogenic activity and melanocytes containing few or no immature melanosomes but showing no cellular alterations. Depigmentation in IGH seems to occur in two stages, loss of melanogenic activity in certain malanocytes and elimination of inactive melanocytes. The basic defect in IGH melanocytes may reflect the aging process.

Hypopigmented mycosis fungoides: report of five cases with ultrastructural observations

“…including marked dilatation of the rough endoplasmic reticulum, swelling of mitochondria with loss of cristae, and cytoplasmic vacuolation. Similar abnormalities have been reported in a variety of acquired hypopigmentary disorders such as leprosy (Job, Nayar & Narayanan, 1972), halo naevus (Hashimoto, 1974), sarcoidosis (Clayton et al, 1977), vitiligo (Breathnach, 1975), pityriasis versicolor (Breathnach, Nazzaro Porro & Martin, 1975), Vogt-Koyanagi syndrome, incontinentia pigmenti achromians (Morohashi et al> 1977) and idiopathic guttate hypomelanosis (Ortonne and Perrot, 1980), as well as following PUVA therapy (Zelickson, Mottaz & Muller, 1979) and treatment with chemical depigmenting agents (Bleehen et al, 1968;Jimbow et al, 1974). Abnormalities of melanogenesis, characterized in our patients by the production of small spherical incompletely melanized melanosomes, have also been described in pityriasis versicolor (Breathnach etal., 1975) and with depigmenting agents (Bleehen et al, 1968;Jimbow et al, 1974).…”

Annular hypopigmented mycosis fungoides: a novel ringed variant

“…19 The incidence of guttate hypomelanosis increases with age, and because most guttate hypomelanosis lesions occur in sun-exposed skin, a possible etiological role of chronic exposure to UV radiation has been suggested. 20 This is again clinically distinct from our patient.…”

Confetti-like lesions with hyperkeratosis: a novel ultraviolet-induced hypomelanotic disorder?

“…The incidence of IGH increases with advancing age. Because most IGH lesions occur in sun‐exposed skin, a possible aetiological role of chronic exposure to UV radiation was suggested 8 . Previous investigations demonstrated loss of melanin as shown by Fontana–Masson staining, decreased tyrosinase activity by 3,4‐dihydroxyphenylalanine (DOPA) histochemistry, and a reduced number of melanocytes by electron microscopy 9 .…”