Diagnosis difficulty of histiocytosis in the thyroid region of a child: a rare case report with literature review of differential diagnoses

Abstract

Abstract Background Isolated histiocytosis of thyroid region is very rare; clinical history, exam, and radiological aspects are non-specific, and etiological reasoning is quite difficult considering the tremendous number of differential diagnoses. Case presentation This is the case of a 6-year-old girl who came to the emergency room with an acute presentation bulging of the anterior and left lateral regions of the neck. The palpation of the mass showed tenderness; there was no sign of inflammation, nor was there any fistula to the anterior border of the sternocleidomastoid muscle. The patient was stable. She did not have any signs of compression. The initial blood showed anemia and inflammatory syndrome. She underwent cervical ultrasound exam that showed a mass at the expense of the left thyroid lobe; the mass extends through the sub-hyoid muscles to the lateral cervical region. A CT scan with and without contrast injection was performed. It showed a heterogenous mass, which seemed centered in the anterior compartment, and from which it extended to the left lateral compartment, as well as the posterior compartment, invading the prevertebral muscles and englobing the carotid and the internal jugular vein. The patient underwent surgical biopsy. A basal cervical incision was made, dissection with the myo-cutaneous plane. Per-operative observation established that the mass breeched the infrahyoid muscles, as well as the sternocleidomastoid muscle. A biopsy was performed without opening the middle line. The pathological exam showed an eosinophilic granulomatosis, associated with Stembergoid cells. The immune-histochemical exam concluded that the lesion is histiocytosis. The patient underwent a cervicothoracic and pelvic CT scan to rule out systemic forms. The diagnosis of isolated histiocytosis of thyroid region was confirmed. The patient underwent hemithyroidectomy, associated with careful dissection of extension of the mass to lateral compartment of the neck. Postoperative exam showed no abnormalities. No dysphonia and no hypocalcemia were observed. The 8-month follow-up showed satisfactory results, no cervical swelling, and no signs of inflammation or compression. Postoperative naso-fibroscopy was normal. Conclusions The most important takeaway message of this work is that methodical approach of neck masses allows to rule out the most aggressive lesions frequently encountered, which allows clinicians to establish thorough diagnosis and management without further delay.