Cyclooxygenase-2 expression in primary and metastatic Merkel cell carcinoma.

Cyclooxygenase-2 (COX-2) is involved in the development and progression of many tumors, and its inhibition has been shown to block tumor growth. This study examined COX-2 expression in primary and metastatic Merkel cell carcinoma (MCC). Formalin-fixed paraffin-embedded tissues from 26 primary MCCs and 7 lymph node metastases were stained immunohistochemically with a monoclonal antibody directed against COX-2, and the percentage and intensity of staining were analyzed semiquantitatively. Immunopositivity for COX-2 was found in 20 primary tumors (77%), and was diffuse in 16 of them (80%). Staining intensity was strong in 5 tumors (19%), moderate in 6 (23%), and weak in 9 (35%). Five metastases (71%) showed similar staining. Prominent mitotic activity was associated with more diffuse COX-2 immunopositivity. No association was found between COX-2 expression and outcome. This study confirms that most MCCs express COX-2 and shows that COX-2 expression is related to one parameter of aggressive behavior--a high mitotic rate--but not to any others. The possibility of treating MCC with COX-2 inhibitors should be considered.

Cyclooxygenase-2 expression in medullary thyroid carcinoma.

BACKGROUND: Recent studies have demonstrated that cyclooxygenase-2 (COX-2) expression is associated with the carcinogenesis of numerous neoplasms. The aim of this study was to evaluate the role of COX-2 in medullary thyroid carcinoma (MTC). METHODS: Tissue specimens of thyroid neoplasms were obtained from 22 patients with MTC and 15 control subjects with nonmalignant thyroid specimens. RESULTS: This immunohistochemical study confirms the presence of COX-2 in a significant number of MTCs. A large area of staining was noted in only 2 patients in the control group (13%) compared with 18 (82%) in the medullary carcinoma group. On a scale of 0 to 3, the average area of positive staining measured 2.35 in the study group and 0.9 in the control group (p < .0001). The average intensity of staining on a scale of 0 to 5 (deep brown) was 2.15 and 0.8 mm, respectively (p < .001). CONCLUSION: COX-2 is expressed significantly in MTC including a larger area of staining and greater intensity than in nonmalignant thyroid tissue. These findings may have important treatment implications for the use of COX-2 inhibitors in patients with MTC.

Diagnostic value of galectin-3 as a marker for malignancy in follicular patterned thyroid lesions.

BACKGROUND: The determination of malignancy in follicular patterned thyroid lesions is based on postoperative histologic findings. Therefore, affected patients are referred for surgery, although only 20% will have a final diagnosis of malignancy. The aim of this study was to investigate the potential of galectin-3 as a marker of malignancy in these lesions. METHODS: Fifty-four tissue specimens of follicular patterned thyroid lesions were immunohistochemically stained for galectin-3. Area and intensity scores were recorded. RESULTS: Significant differences were found between the benign and malignant lesions. The sensitivity, specificity, positive predictive values, and negative predictive values of galectin-3 staining were 82%, 68%, 75%, and 77%, respectively (p=.0002). Significant differences were also found between the subgroups of benign and malignant lesions (p < or =.05). CONCLUSIONS: Galectin-3 staining is highly sensitive for malignancy in follicular patterned thyroid lesions. Diagnostic problems may arise in the presence of Hurthle cell proliferation or minimally invasive follicular carcinoma.