Insular carcinoma: A distinct de novo entity among follicular carcinomas of the thyroid gland

Silvana Pilotti, Paola Collini, Luigi Mariani, Marco Placucci, Italia Bongarzone, Paolo Vigneri, Sonia Cipriani, Francesca Falcetta, Rosalba Miceli, Marco A. Pierotti, Franco Rilke

Research output: Contribution to journalArticlepeer-review


We reclassified 720 nonmedullary invasive thyroid carcinomas diagnosed and treated between 1975 and 1993. Twenty-seven cases met the criteria of insular carcinoma and 29 cases those of widely invasive follicular carcinoma. Comparison of these histotypes with respect to pathologic stage and overall, relative, and visceral metastasis-free survival showed a significant association between histotype and pT and pN categories. In particular, pT4 (p <0.001) and pN1 (p <0.001) categories were more frequent in the insular carcinoma histotype. By contrast, no significant differences in overall, relative, or visceral metastasis-free survival were observed between insular carcinoma and widely invasive follicular carcinoma. Molecular analysis by polymerase chain reaction-single-strand conformation polymorphism demonstrated RAS gene family point mutations in five of eight cases analyzed in each of the two histotypes, with a high proportion of CAA→AAA transversion at codon 61 of the N-RAS gene in insular carcinoma. These findings suggest that insular carcinoma represents a de novo entity distinct from widely invasive follicular carcinoma, that widely invasive follicular carcinoma has biologic characteristics more consistent with poorly differentiated than well-differentiated carcinomas, and that both insular carcinoma and widely invasive follicular carcinoma share similar molecular alterations.

Original languageEnglish
Pages (from-to)1466-1473
Number of pages8
JournalAmerican Journal of Surgical Pathology
Issue number12
Publication statusPublished - 1997


  • Insular carcinoma
  • Molecular analysis
  • Poorly differentiated carcinoma
  • RAS gene family point mutations
  • Statistical analysis
  • Thyroid gland

ASJC Scopus subject areas

  • Anatomy
  • Pathology and Forensic Medicine


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