A 47-year-old man presents with neck pain. A mass at the level of the thyroid is detected at physical exam and imaging, and a hemi-thyroidectomy is performed.
Correct Answer: C. Langerhans cell histiocytosis (LCH)
LCH is a process of ubiquitous distribution in the human body and it has been described in many organ systems. However, the presence of solitary LCH in the thyroid is rather rare. When reported, LCH has been associated with other conventional tumoral conditions, such as papillary carcinoma or follicular carcinoma of the thyroid. The diagnosis of LCH can be done on morphological evaluation and is aided by the expression of S-100, CD1a, and langerin, which are positive in LCH.