Diffuse sclerosing variant of papillary carcinoma of the thyroid. A histopathological study of four cases

Diffuse sclerosing variant of papillary thyroid carcinoma: a clinicopathologic and immunophenotypic analysis of 22 cases

BACKGROUND

The diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) is an uncommon tumor making up about 2% of all papillary thyroid carcinomas. Previous studies have not comprehensively evaluated these tumors in a large series of patients.

DESIGN

Twenty-two cases of DSV-PTC diagnosed between 1970 and 2000 were identified in the files of the AFIP. Histologic and immunohistochemical features were evaluated and patient follow-up was obtained.

RESULTS

The tumors affected 14 females and 8 males, aged 6 to 49 yr (mean, 18 yr), with males presenting at a mean older age than females (24 vs 14 yr). Symptoms included an enlarging mass in the thyroid, present for a mean of 9.5 mo. While a dominant tumor was identified in a single lobe, bilateral disease was common (n = 16). The dominant mass ranged in size from 1.7 to 5.8 cm in diameter (mean, 3.8 cm). Histologically, all cases demonstrated a papillary carcinoma (conventional, solid, or follicular pattern) diffusely involving the gland. Extrathyroidal extension, lymphocytic thyroiditis, squamous metaplasia, increased fibrosis/sclerosis, and psammoma bodies were present to a variable degree. Both the papillary carcinoma and squamous metaplasia cells were strongly immunoreactive with CK19, thyroglobulin, and TTF-1. An increased number of S-100 protein immunoreactive dendritic cells were recognized. p53 was increased (>15%) in the tumor cells in 12 patients, while Ki-67 was increased in the tumor cells in two patients. Perithyroidal and cervical lymph node metastasis occurred in 18 (82%) patients. All metastases demonstrated histologic features similar to the primary. Complete resection (thyroidectomy in 18 patients) with lymph node dissection, yielded a 95% 5-yr survival without evidence of disease. One patient died of disease after a malignant transformation of the squamous metaplasia into squamous cell carcinoma.

CONCLUSIONS

The recognition of DSV-PTC can be made with the following features: classic to solid foci of PTC, lymphocytic thyroiditis, squamous metaplasia, increased fibrosis, and innumerable psammoma bodies. DSV-PTC is more biologically aggressive than conventional PTC, but the patients' survival is not significantly different. This diagnosis should lead the clinician to aggressively manage these patients (thyroidectomy and lymph node dissection) in an effort to achieve an excellent long-term clinical outcome.

Diffuse sclerosing variant of papillary thyroid carcinoma with primary squamous cell carcinoma

A case of a very rare combination of diffuse sclerosing variant of papillary thyroid carcinoma (DSPC) and primary squamous thyroid carcinoma (PSC) is presented. A 25-yr-old woman with right-sided neck mass and hypothyroidism was admitted. US showed that the right lobe of the thyroid gland was enlarged with irregular margins and heterogen echogenity and there were multiple small punctate echogenic foci in the central portion. A scintigraphy with 99mTc showed decreased uptake in the right lobe. FNA of the right lobe induced us to consider the presence of follicular neoplasm. Chest roentgenogram was normal. Total thyroidectomy with right-sided modified radical neck dissection was performed. Findings related to Hashimoto's thyroiditis and abundant psammoma bodies were observed in the frozen sections. Histopathologic findings demonstrated the coexistence of DSPC and PSC in both lobes and 16 lymph nodes metastases and soft tissue infiltration. Radioiodine was administered to ablate residual thyroid tissue. She was given T4 suppression therapy. At the 44th month of follow-up, she remains well without recurrences and metastases. The coexistence of DSPC and thyroiditis or PSC is still under debate. Very few cases with the combination of papillary thyroid carcinoma and PSC have been reported previously, thus we discuss the clinico-pathologic features and possible explanation for this unusual coexistence of malignancies.