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Morules in cribriform‐morular variant of papillary thyroid carcinoma: Immunohistochemical characteristics and distinction from squamous metaplasia
Author(s) -
HIROKAWA MITSUYOSHI,
KUMA SEIJI,
MIYAUCHI AKIRA,
QIAN ZHI RING,
NAKASONO MASAHIKO,
SANO TOSHIAKI,
KAKUDO KENNICHI
Publication year - 2004
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1600-0463.2004.apm11204-0508.x
Subject(s) - pathology , histogenesis , metaplasia , squamous metaplasia , immunohistochemistry , cytokeratin , columnar cell , biology , epithelium , medicine
Morules are a diagnostic clue to the cribriform‐morular variant (C‐MV) of papillary thyroid carcinoma, and are superficially similar to squamous metaplasia. In order to clarify the histogenesis of morules and differentiate them from squamous metaplasia, we immunohistochemically compared the morules in five cases of C‐MV with squamous metaplasia in six cases of diffuse sclerosing variant (DSV) of papillary thyroid carcinoma. The squamous metaplastic cells were immunopositive for low‐ and high‐molecular‐weight cytokeratin, whereas the morular cells were negative or focally positive. Vimentin‐positive cells were observed focally in the morules and squamous metaplasia, except for one case of CMV that showed intense positivity. The morular cells showed weak cytoplasmic positivity for beta‐catenin, and the cell membrane was not highlighted. Some nuclei of the morular cells were also positive for this antibody. Beta‐catenin was intensively positive along the cell membrane of the metaplastic cells, and did not react against the nuclei or cytoplasm. Bcl‐2 was positive in the morular cells, but negative in the metaplastic cells. S‐100 protein‐positive dendritic cells were observed in the metaplastic nests, but not in the morules. We argue that morules appear in connection with nuclear and cytoplasmic aberrant localization of beta‐catenin, and are not an early form of squamous metaplasia.