A 64 year-old female with scalp metastasis of papillary thyroid cancer.

The skin metastasis of papillary thyroid carcinoma (PTC) is a rare condition and the lesions should be differentiated from primary skin tumors. The scalp is the most frequent site which is involved in skin metastasis of PTC. It shows the poor outcome and aggressive nature of disease. In this report, we aim to present a case report of a 64 year-old female with scalp metastasis of PTC in the context of disseminated pulmonary and liver metastasis.

INTRODUCTION

Papillary thyroid carcinoma (PTC) is the most frequent type of thyroid malignancy, and the usual metastasis sites include the locoregional lymph nodes. Distant metastasis of PTC is rare and usually involves the lungs, liver, bones and brain.[1] The skin metastasis of PTC is a very rare condition, and the scalp is the most frequent cutaneous area which is involved. Other cutaneous areas that are involved with less frequency are the cheeks, shoulders, arms, abdomen and thighs.[12]

CASE REPORT

A 64 year-old female with past medical history of metastatic papillary thyroid carcinoma (PTC) with both liver and lung metastasis presented with a 2.5 × 3 cm erythematous tender nodule in right parietal scalp of two months duration. She had a past medical history of total thyroidectomy and also had received repeated doses of radioactive iodine (RAI) therapy in the past two years. Her last dose of RAI131 (200 mCi) was three weeks prior to the time of presentation. She also had a history of subglottic mass as a result of thyroidal carcinoma involvement with severe tracheal stenosis, and had undergone tumoral resection and tracheal anastomosis and partial hemilaryngectomy two years ago because of subglottic involvement by thyroidal carcinoma. She was under treatment with thyroid stimulating hormone (TSH)–suppressive therapy with levothyroxine.

High resolution computed tomography (HRCT) demonstrated multiple metastatic nodules in both lungs and loculated left side pleural effusion consistent with advanced metastatic involvement. A differential diagnosis of pillar cyst and metastasis was given by dermatologist for scalp lesion. Excisional biopsy was carried out. Histopathologic examination of the lesion revealed skin tissue with tumoral involvement of the dermis composed of numerous follicles (likely thyroid follicles), lined by relatively large cuboidal epithelial cells with round nuclei, fine chromatin pattern, little granular cytoplasm and eosinophilic colloidal material within some of follicles, and mitosis, which was consistent with metastatic thyroidal carcinoma [Figures 1 and 2]. She was discharged with suppressive therapy with levothyroxine and referred to oncology clinic for continuation of the treatment plan.

Figure 1

Scalp lesion biopsy showing skin tissue with tumoral infiltration of dermis by numerous follicles (likely thyroid follicle), consistent with metastatic thyroidal carcinoma (H and E, ×40)

Figure 2

Scalp metastasis of thyroidal carcinoma composed of numerous follicles lined by relatively large cuboidal epithelial cells with round nuclei, fine chromatin, little granular cytoplasm and eosinophilic colloid material within some of follicles with mitotic division (H and E, ×400)

DISCUSSION

The skin metastasis of PTC is mostly associated with aggressive and disseminated disease and shows a poor outcome.[3] Some authors suggested that the average patient survival time after discovering of skin metastasis is 19 months.[13] Here, we have reported a case of scalp metastasis of PTC in a patient with metastatic pulmonary and liver involvement. Metastasis of thyroid cancer should be considered in the differential diagnosis of scalp tumors in any patient with a history of thyroidal carcinoma; and, excisional skin biopsy is necessary for confirming the diagnosis.