Hypopigmented mycosis fungoides (HMF) is an uncommon variant of mycosis fungoides with an unknown exact frequency. We aimed to study the frequency of HMF in a cohort of Egyptian patients presenting to a tertiary care center in Cairo, Egypt, with hypopigmented lesions of the trunk. Hundred patients with hypopigmented lesions involving the trunk (with or without other sites involvement) were subjected to thorough clinical and histopathological examination. Immunohistochemical studies (S100, CD4, and CD8) were performed when indicated. Constellation of findings was used to reach a final diagnosis. Sixteen cases had HMF (16%). Other than HMF, our cohort included hypopigmented parapsoriasis en plaque (42 cases), postinflammatory hypopigmentation (28 cases), progressive macular hypomelanosis (12 cases), and pityriasis alba (2 cases). In comparison with other hypopigmented disorders, HMF was significantly associated with progressive disease course (P = 0.004), affection of distal upper limbs (P = 0.005), proximal lower limbs (P = 0.003), large-sized lesions (>5 cm) (P < 0.0001), well-defined margin (P < 0.0001), scaliness (P = 0.002), erythema (P < 0.0001), atrophy (P = 0.012), and mottled pigmentation (P < 0.0001). Awareness of HMF and its characteristic clinical features is mandatory to avoid underdiagnosis or overdiagnosis with subsequent morbidity or unnecessary aggressive therapy, respectively.

BackgroundS100B protein was reported to be elevated in psoriatic patients' serum, with no previous evaluation of its skin expression, in contrast to the extensively studied S100 protein.ObjectiveTo evaluate the serum level and skin expression of S100B in psoriasis to assess its possible involvement in its pathogenesis.MethodsSerum level of S100B protein was estimated in 40 psoriatic patients of different clinical varieties and 10 healthy controls. S100B protein expression was assessed immunohistochemically in lesional and non-lesional skin of patients and in normal skin of controls. Relation to disease severity was also evaluated.ResultsSerum level of S100B protein was significantly higher in psoriatic patients (0.15±0.03 µg/l) than in controls (0.03±0.007 µg/l) (P-value <0.001) with no significant correlation with PASI score. On comparing grades of S100B protein skin expression in lesional and non-lesional skin biopsies, a statistically significant difference was found (P=0.046) with higher percentage of strong S100B skin expression (60%) in non-lesional than in lesional (42%) skin. All the control biopsies showed negative expression.Study limitationsRelatively small sample size with a limited range of low PASI scores.ConclusionThis study points to a potential link between psoriasis and S100B protein with higher serum and skin expression in patients than in controls.