Pathological thyroid findings in amiodarone-induced thyrotoxicosis.

Amiodarone (AMD) is a class III antiarrhythmic drug whose chronic or high dosage administration alters the tests of thyroid function. AMD is also associated with hypothyroidism or thyrotoxicosis. Total thyroidectomy is an efficient treatment of AMD-induced thyrotoxicosis in cases resistant to medical therapy, worsening of cardiac function and/or severe thyrotoxicosis. Although AMD is a widely used drug, its pathological consequences are not well known. We describe the pathological findings in the thyroid gland of a patient who underwent total thyroidectomy due to AMD-induced thyrotoxicosis. The surgical specimen was macroscopically normal, but histologically showed multiple follicles totally or partially invaded by clear vacuolated (foamy) histiocytes, sometimes multinucleated. Loss of thyrocytes, breaks in the follicular basal membrane and stromal fibrosis could also be appreciated but no lymphocytic infiltrates were found. An awareness of these histopathological features is particularly important for surgical pathologists, especially as there are very few published reports describing these alterations.

Evaluation of a Clinical Pathway for Thyroid Nodular Disease: Timings and Delays in the Diagnosis and Treatment of Thyroid Cancer.

BACKGROUND: Due to the high prevalence of nodular thyroid disease in the general population and the need to rule out malignant tumours, a clinical pathway for nodular thyroid disease was created at our tertiary-level hospital. Our study aimed to quantify timings and delays in diagnosis and treatment in this clinical pathway, specifically for patients who were diagnosed with thyroid cancer. METHODS: A retrospective review was conducted of patients who were newly diagnosed with thyroid cancer and who had been previously evaluated in the clinical pathway for nodular thyroid disease at our institution during 2015-2017. Patient demographics, previous diagnostic studies, cytological results, tumour details and key dates were analysed to identify wait times in diagnosis and treatment. RESULTS: Forty patients with thyroid cancer were included. The diagnostic delay had a median time of 60 days, and the treatment delay was dependent on cytopathological results. The main cause for delay in the diagnostic phase was the timing of the thyroid ultrasound performed by the radiology department. In the treatment phase, patients with a cytological result of Bethesda III, V or VI underwent surgery at the suggested time, while those in the Bethesda II or IV category did not. CONCLUSIONS: The major delay found in the diagnostic phase was the timing of the thyroid ultrasound performed by the radiology department. We are not suggesting that this step must be eliminated, though the implementation of routine ultrasonography in a thyroid clinic can help identify patients who need more urgent evaluation for fine needle aspiration cytology. In our hospital, decision for surgery is based mainly on the cytopathological report. Imaging studies and/or molecular testing could be considered to reduce treatment delays.

Merkel cells of human oral mucosa express the pluripotent stem cell transcription factor Sox2.

Merkel cells are neuroendocrine cells associated to a neural sensitive ending and localized primarily in the epidermis, although they are also found in oral mucosa. Sox2 or SRY-box2 is a key transcription factor important in the maintenance of embryonic neural crest stem cell pluripotency. Sox2 has been described in Merkel cells of skin and in Merkel cell carcinomas, but not specifically in oral Merkel cells. The aims of the present study were to analyze the density of Merkel cells in human oral mucosa and to study the expression of Sox2 in these cells. For these purposes, immunohistochemical analyses for Sox2 and CK20 (the best marker for Merkel cells) were automatically performed on sections of normal human oral mucosa. Double immunofluorescence for Sox2 and CK20 was also performed. To analyze the density of Merkel cells, CK20 positive cells were counted in each sample and the length of the epithelial apical edge was measured (cells/mm). Merkel cells, demonstrated by CK20 immunoreactivity, were found in 95% of oral mucosa specimens studied (n=21). Mean density of Merkel cells in oral mucosa was 1.71±2.34 cells/mm. Sox2 immunoreactivity was found in the nuclei of scattered cells located at the basal layer. Serial sections immunostained for Sox2 and CK20 showed that Sox2-positive cells of oral mucosa coexpressed CK20, confirming that they were Merkel cells. Immunofluorescence for Sox2 and CK20 showed colocalization of both markers, demonstrating that virtually all oral Merkel cells expressed Sox2. This transcription factor could play a role in Merkel cell maturation and maintenance.