Isolated Skin Metastasis From Papillary Thyroid Carcinoma: A Rare Presentation

Abstract

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy and is often characterized by a high rate of regional lymph node involvement. However, distant metastasis is uncommon, and cutaneous metastases are particularly rare, occurring in fewer than 0.1% of cases. This report presents an unusual case of isolated skin metastasis as the first manifestation of distant spread in PTC. The case highlights the diagnostic challenges associated with this rare presentation, explores potential mechanisms underlying cutaneous dissemination, and underscores the significance of a multidisciplinary approach to management. The findings emphasize the importance of long-term surveillance and meticulous pathological evaluation in patients with PTC, particularly in cases with atypical metastatic patterns.

Keywords: metastatic thyroid carcinoma; papillary thyroid carcinoma; rare case; skin metastasis; thyroid cancer.

Figure 1.

Neck ultrasound reveals a 1.1 × 1.5 × 1.9 cm nodule in the right lobe with the following characteristics based on the ACR TI-RADS: solid composition (2 points), hypoechoic echogenicity (2 points), wider-than-tall shape (0 points), smooth margin (0 points), and no echogenic foci (0 points). The total score is 4 points, classifying the nodule as TI-RADS 4. Abbreviations: ACR-TI-RADS, American College of Radiology Thyroid Imaging Reporting and Data System.

Figure 2.

A solitary, well-circumscribed, raised lesion located on the anterior aspect of the lower neck above the total thyroidectomy scar. The lesion is erythematous, dome-shaped, and smooth-surfaced, measuring approximately 0.8 cm in diameter (A). Histopathological examination of the shave biopsy stained with hematoxylin and eosin reveals tumor cells arranged in papillary structures with fibrovascular cores. these cells exhibit characteristic nuclear features, including enlarged nuclei with cleared chromatin (“Orphan Annie eye”), nuclear grooves, and occasional intranuclear inclusions, confirming the diagnosis of metastatic papillary thyroid carcinoma (B).

Figure 3.

Positron emission tomography/computed tomography imaging from the skull to mid-thigh reveals hypermetabolic activity in the cutaneous lesion in the right anterior lower neck (arrow) (A), the lymph node lesion in the right anterior lower neck (arrow) (B), and the nodule in the right upper lobe of the lung (arrow) (C).

Figure 4.

The nodule in the right upper lobe, previously detected on the CT component of the PET/CT scan (circled) (a), is no longer visible on the follow-up CT scan (B). Abbreviations: CT, computed tomography; PET, positron emission tomography.