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Extensive pityriasis alba: A histological histochemical and ultrastructural study
Author(s) -
ZAYNOUN S.T.,
AFTIMOS B.G.,
TENEKJIAN K.K.,
BAHUTH N.,
KURBAN A.K.
Publication year - 1983
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.1983.tb04582.x
Subject(s) - melanosome , ultrastructure , vacuolization , hypopigmentation , parakeratosis , histology , pathology , hyperkeratosis , acanthosis , biology , cytoplasmic inclusion , dermatology , cytoplasm , medicine , melanin , microbiology and biotechnology , genetics
SUMMARY Nine patients with extensive pityriasis alba were studied using histopathological and histochemical techniques and electron microscopy. There was a reduction in the density of functional mclanocytes in the affected areas without any change in their cytoplasmic activity. The melanosomes tended to be fewer and smaller, but their distribution pattern in the keratinocytes was normal. Melanosomal transfer to keratinocytes was generally not disturbed. The histology was non‐specific. Hyperkeratosis and parakeratosis were not consistently present, and it seems unlikely that they played a significant role in the pathogenesis of the hypomelanosis. A variable degree of intercellular oedema and intracytoplasmic lipid droplets were present. The hypopigmentation may thus be due primarily to the reduced numbers of active melanocytes and a decrease in number and size of melanosomes in the affected skin.