Neuroendocrine differentiation in basal cell carcinomas: a retrospective immunohistochemical and ultrastructural study.

Recent investigations have suggested that in addition to basaloid cells, basal cell carcinomas (BCC) may also contain Langerhans cells and neuroendocrine cells. In order to establish the relative frequency of neuroendocrine differentiation in BCC, we performed a retrospective study of 50 consecutive BCC using conventional histochemical, immunocytochemical and ultrastructural methods. Argyrophil staining according to Grimelius was used for initial identification. Tumors containing argyrophil cells, as well as randomly selected tumors without these cells, were immunocytochemically stained with a panel of antisera against neurohormonal peptides. Only 2 tumors with argyrophil cells showed occasional somatostatin immunoreactivity; peptide hormone immunoreactivity could not be detected in any of the others. The somatostatin immunoreactive tumors, as well as 3 others, were subjected to electronmicroscopy to study the presence of dense-core secretory granules. However, these characteristic intracytoplasmatic structures could be detected in none. It is concluded that if neuroendocrine differentiation exists at all in BCC, it must be extremely rare. Our results indicate that reliable identification of multiple lines of differentiation in neoplasms can only be performed using combinations of (immuno) histochemical and ultrastructural techniques.