Morphological and immunohistochemical clues for the diagnosis of cutaneous leishmaniasis and the interpretation of CD1a status

Background: CD1a immunoexpression by amastigotes of Leishmania major and L tropica has been demonstrated. Objective: We studied the CD1a and the langerin status of amastigotes in cases of L infantum. Methods: We investigated 19 cases of cutaneous leishmaniasis. All cases were immunostained with CD1a, langerin, and CD68. We also studied 4 cases of visceral leishmaniasis. Results: We found expression of CD1a by amastigotes in all of these 19 cases. CD1a(-) amastigotes are found in reticular areas of the dermis. The pattern of CD1a immunostaining of amastigotes is characteristic, with peripheral positivity, a negative nucleus in the center, and reinforcement of the kinetoplast in 1 pole. Leishmania amastigotes were langerin-negative. Visceral Leishmania amastigotes also express CD1a. Limitations: Our study was limited because it only included cases of infection by L infantum. Conclusions: (1) L infantum is CD1a(+), (2) the pattern of CD1a immunostaining of amastigotes is peculiar, (3) CD1a(-) amastigotes are found in reticular areas of the dermis, and (4) visceral Leishmania amastigotes also express CD1a.