Histomorphological Spectrum of Papillary Carcinoma of Thyroid in Oman

Thyroid cancer is the commonest endocrine malignancy and is the second most common cancer affecting young females in Oman. The diagnosis of Papillary Thyroid Carcinoma (PTC) is based primarily on histologic architecture and nuclear morphology in routine Haematoxilin and Eosin (HE) stained slides. Whenever in doubt, immunohistochemistry may be helpful. This retrospective study included 115 cases of PTC diagnosed at a tertiary care center in Oman over 10 years period, from 2001 to 2010. Slides and blocks of these cases were retrieved from the pathology laboratory. Ninety five (95) were females and 20 were males. Papillary Thyroid Carcinoma (PTC) was most commonly seen in the 20 - 50 years of age. The commonest morphologic variant seen in this population was classical papillary variant in 44/115 (38%) followed by papillary micro-carcinoma (n=30/115, 26%) and follicular variant of papillary carcinoma (n=18/115, 15.6%). Out of the 30 micro-carcinoma cases, 18 were diagnosed incidentally in thyroids operated for multi-nodular goiter. Immunohistochemical marker CK-19 was positive in 29/31, HBME-1 and HMW-CK in 15/15 cases; CEA was in one case where it was reported negative. Immunohistochemical stains were useful in cases with atypical /doubtful morphology.