nuclear moulding nuclear moulding in histopathology, nuclear moulding, also nuclear molding, is conformity of adjacent cell nuclei to one another. micrograph of a small cell carcinoma showing cells with nuclear moulding. fna specimen. field stain. it is a feature of small cell carcinomas and particularly useful for differentiation of small cell and non-small cell carcinomas, i.e. adenocarcinoma and squamous carcinoma.