Background: “Black thyroid” (BT) has been reported as a rare and harmless
phenomenon associated with the administration of minocycline and related
tetracyclines. However, other drugs, including indocyanine green and
antidepressants, have been demonstrated to be rarely associated with BT.
BT consists of brown to black pigment accumulation in the cytoplasm of
follicular thyroid cells conferring a diffuse black macroscopic appearance.
The pathogenesis of such thyroid lesion is not still entirely clear.
Clinical history: A 68-year-old woman, known for a longstanding multinodular
goitre with hyperthyroidism unsuccessfully treated with carbimazole,
underwent total thyroidectomy. Her past medical history also included
anxiousdepressive troubles treated with paroxetine, type II diabetes,
arterial hypertension, dyslipidemia, osteoporosis, and occasional unspecific
muscular pain. The patient was not treated with minocycline or other
tetracyclines. A thyroid scintigraphy showed a hyperactive left nodule
and a hypoactive right nodule. Cytoponction of the left lobe was initially
not informative due to insufficient material, while the second one showed
a benign thyroid lesion (classification: Bethesda II), characterized by the
presence of a brown pigment in the cytoplasm of follicular cells.
Results: Thyroidectomy specimen consisted of left (5.5x3.1x2.8 cm) and
right lobe (4x1.5x2 cm; total weight 25.1gr). On cut section, both lobes
showed multinodularity and a diffuse black color predominant in the left
lobe. Moreover, left lobe showed microcysts and calcifications. A right
0.9 cm beige non encapsulated nodule was found. Histologically, a multinodular
goitre with dilated follicles of varying sizes with flattened to hyperplastic
epithelium and degenerative changes (scarring, focal hemorrhage
and calcifications) was observed. Abundant dark brown, granular,
dust-like cytoplasmic pigment in the apical portion of follicular cells was
noticed. This pigment was negative for Fontana-Masson, Prussian blue,
and VonKossa stainings and positive at Periodic acid-Schiff staining with
or without diastase.
Conclusions: We describe the cytological and histological features a rare
case of antidepressants-related BT.