Originally, expression of the CD30 antigen was shown to be typical of the tumor cells of Hodgkin disease and of anaplastic large cell lymphomas. In reactive lymphoid tissue, CD30 is expressed only in a small population of activated lymphoid blasts. Since then, several reports have been published describing CD30 expression in non lymphoid tissues and neoplasms, such as embryonal carcinomas, seminomas, cultivated macrophages, histiocytic neoplastic cells, deciduals cells, and mesothelioma cells. In order to gain insight into the functions of CD30, given that it can mediate signals for cell proliferation and apoptosis, we studied the distribution of the antigen in different fetal archival paraffin-embedded tissues from week 8th to 16th of gestation. We investigated the immunohistochemical expression of CD30 in 30 paraffin-embedded tissue samples representing all three germ layers, using the monoclonal antibody Ber-H2 CD30 is expressed early in human fetal development (8th–10th week) in a wide variety of tissues, with the exception of the skin and thymus in which it is expressed later on. This is consistent with the observation that these organs are not fully differentiated before 10th and 13th week, respectively. No expression was observed in the cardiovascular and respiratory systems. The finding of CD30 expression in the terminal period of organogenesis, period, which is highly hormone related, implies that the antigen has an important role in cell development, maturation, and pathway to terminal differentiation in almost all fetal tissues and structures.

        Key words: CD30 antigen – fetal tissues – 8th–16th week of gestation