Thyroid carcinoma showing squamous differentiation throughout the entire lesion is diagnosed as
squamous cell carcinoma of the thyroid (SCCT) in the WHO classification. This entity is a
rare disease and shows a dire prognosis; however, squamous differentiation is more frequently detected in only a portion of
papillary thyroid carcinoma. In this paper, we present our experience of 10 patients (8 primary lesions and 2 with recurrence in the lymph nodes) with
papillary thyroid carcinoma having an SCC component (PTC-SCC). Only 3 of 8 primary lesions (38%) and none of the 2 recurrent nodes were preoperatively diagnosed as or suspected of having SCC components. All 10 patients underwent locally curative surgery. To date, 3 patients have died of
carcinoma, and 2 had distant
metastasis at diagnosis or had an
undifferentiated carcinoma component. The other 7 are currently alive 5 to 43 months after diagnosis. Systemic adjuvant
therapy after the detection of recurrence was effective for 2 patients. It is possible that some PTC-SCC patients without distant
metastasis who undergo locally curative surgery can survive for a prolonged period and adjuvant
therapies can be effective for local and distant recurrences.