ESPE Abstracts

Introduction: A 23-month-old male was admitted for evaluation of an enlarging neck mass, persistent rash, and periorbital edema.

Case Description: The toddler had a strikingly large neck mass which had rapidly progressed over 1 month. He presented with a pustular and petechial rash primarily on his scalp which had been unresponsive to multiple treatment modalities. Initial work-up for his neck mass revealed a TSH of 19.7mU/L (0.4-6.0mU/L). His TSH on the Newborn Metabolic Screen was normal. He consumed an iodine replete diet. Anti-thyroglobulin and anti-thyroid peroxidase antibodies were negative. Repeat TSH was 28.6 mU/L and free T4 was 6.8 pmol/L (8.0-20.0pmol/L). Thyroid ultrasound demonstrated a diffusely enlarged and hypervascular gland, indicating high metabolic activity which is atypical in a biochemically hypothyroid patient.

The initial biopsy of his skin lesions was suboptimal for evaluation and did not show any obvious inflammatory infiltrate. There was no suggestion of infiltrative disease based on liver enzymes and peripheral blood smear. Lymphopenia was identified and the working diagnosis shifted towards an immunodeficiency. Fine needle aspiration of the thyroid revealed atypical histiocytic infiltrate consistent with Langerhans Cell Histiocytosis (LCH). No normal thyroid elements were identified.

CT neck revealed a large soft tissue mass within the anterior neck exerting significant mass effect on the subglottic airway. The narrowest tracheal segment measured 6mm anterior to posterior.

Discussion: The patient was diagnosed with multisystem LCH. His acquired hypothyroidism was a result of LCH infiltration of the thyroid and compression of the normal thyroid glandular tissue. Toddlers rarely present with acquired primary hypothyroidism, and this case highlights the importance of considering infiltrative disease as an etiology in this age group. The patient required intensive care admission and was urgently treated with corticosteroids to manage the airway. It is crucial to consider and urgently manage external compression of the trachea and neck vessels when faced with a rapidly enlarging neck mass.