Abstract

Objective: Neuroendocrine (NE) differentiation has been detected and suggested as an indicator of poor prognosis in a subgroup of a variety of carcinomas, including the pulmonary neuroendocrine carcinomas (PNECs) which express multiple NE cell markers. With the hypothesis that histidine decarboxylase (HDC) and its mechanism of releasing and regulating biogenic amines and peptides, may outline a significant link between NE differentiation of any malignancy, we studied the immunohistochemical expression of this marker, along with chromogranin A (CgA), in various subtypes of PNECs.

Material and Method: A cross-sectional descriptive study was carried out comprising 125 patients of PNECs, with the formalin fixed, paraffin embedded tissue blocks which, after H/E staining, were subjected to immunohistochemistry (IHC) with monoclonal anti-HDC and anti CgA antibodies. Positive staining was asserted following the criterion proposed in the previous literature.

Results: Our findings of the study revealed that HDC immunostaining in the PNECs demonstrated much better positivity, i-e 88%, as compared to CgA which was positive in only 57.6% cases (P<0.001). The association of positive HDC and CgA immunostaining with the histological grades of PNECSs, showed a notably enhanced positivity by the latter in PD tumours, of which 89.3% were strongly positive as compared to CgA, which was positive in 54.3% cases (P<0.001).

Conclusion: HDC may be applied as a reasonably reliable marker for demonstrating NE differentiation in PNECs, regardless of their degree of differentiation as compared to the dependence of CgA positivity on the differentiation of a particular malignancy.