An Unusual Subcutaneous Metastasis from Anaplastic Thyroid Carcinoma: A Case Report

Abstract

Author(s): K. Soussy1,2,3, M. Chrifi Alaoui1,2,3, W. Hassani1,2,3, FZ. Farhane1,2,3, Z. Alami1,2,3, T. Bouhafa1,2,3

Background: Anaplastic thyroid carcinoma (ATC) is a rare and highly aggressive malignancy with a high risk of early metastatic dissemination. Cutaneous and subcutaneous metastases are uncommon. We report an unusual case of an isolated subcutaneous abdominal wall metastasis followed by isolated mediastinal nodal progression, both managed with local treatment. Case presentation: A 70-year-old woman underwent thyroidectomy for clinically staged T4aN0M0 thyroid carcinoma. Initial biopsy showed papillary thyroid carcinoma, whereas the thyroidectomy specimen demonstrated coexisting papillary and anaplastic carcinoma components. The anaplastic component was positive for CK8/18 and negative for thyroglobulin and p53. Adjuvant chemoradiotherapy consisted of IMRT to 70 Gy in 35 fractions with seven weekly cycles of carboplatin. Three months after treatment, CT revealed an isolated 14.5-mm subcutaneous mass in the left lateral abdominal wall. Biopsy confirmed anaplastic carcinoma with an immunophenotypic profile concordant with the thyroid anaplastic component. The lesion was completely resected. Three months later, PET/CT revealed an isolated 15-mm hypermetabolic mediastinal lymph node in station 4R (Barety region; SUVmax 6.8). The lesion was subsequently treated with SBRT to 56 Gy in eight fractions. Conclusion: This case illustrates an uncommon pattern of sequential oligometastatic ATC. Careful pathological assessment, close surveillance, multidisciplinary decision-making, and individualized local treatment may be considered in selected patients with limited metastatic disease.

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