Black thyroid (black thyroid syndrome) is very rare, with only 61 cases reported in 2010. I never found one and I do not know a surgeon who has. However, all surgeons should know it is possible to find a black thyroid and should also know the meaning of this interesting finding. Keep calm, it is just a dark gland.
Paola Solis-Pazmino et al from the Department of Otolaryngology from the Stanford University School of Medicine, California, USA, recently reported a case of this rare entity. They studied a 23 yo female patient who was diagnosed with a 17 mm thyroid nodule. Fine needle aspiration biopsy diagnosed a Bethesda IV. A total thyroidectomy was proposed. During surgery, a dark-colored thyroid was found without deformities. Pathology concluded for a follicular adenoma. Patient recovery was uneventful.
Black thyroid is an intra operative finding since it is not diagnosed by FNA.
The first idea that comes up to my mind was the aggressive treatment these authors proposed to a young female patient. Preoperative diagnosis was not cancer, she had a unique nodule in the right lobe of the gland, and although ultrasonography had shown microcalcifications there were no cervical adenopathies (ok, it was a follicular lesion…). A right lobectomy with isthmectomy would have been my first-line treatment. If cancer would come in pathology, then I would remove the remaining gland. Total thyroidectomy has a higher risk for severe postoperative complications, namely: bilateral RLN injury (can result in life-threatening airway obstruction); severe hypocalcemia (sometimes difficult to treat) resulting from unintentional resection of parathyroids (or devascularization). The risk for unilateral injury of RLN is also higher since both nerves are dissected. Unilateral nerve injury impairs the voice and swallowing. In this setting, more surgeons are now adopting gland tissue sparing strategies. In the end, the patient had no cancer and no thyroid. Did it worth the risk? Was the risk unnecessary?
The black thyroid was an interesting intraoperative finding. The authors did not panic because they knew what it was and why. A good preoperative evaluation had been conducted and the justification was obvious. In fact, surgeons should expect a black thyroid in a patient like the one reported. Paola Solis-Pazmino knew the young female patient had been treated with minocycline for acne. Minocycline reacts with thyroid peroxidase to form a dark pigment that accumulates in lysosomes and macrophages and is responsible for the dark thyroid. As far as we know, there is no impact on the gland’s functionality. By knowing this, the authors easily calmed down the patient. Black thyroid has also been reported in cystic fibrosis, treatment with other tetracyclines, and hereditary hemochromatosis and ochronosis.
There is no evidence of increased incidence of thyroid cancer in patients with black thyroids. Unfortunately, there is no absolute truth.
Two questions arise. Is black thyroid a risk factor for cancer? Should an intraoperative finding of a black thyroid change our preoperative decision of a hemithyroidectomy? There are reports of a 30% incidence of thyroid cancer in patients with black thyroids as opposite to the 0,003% incidence in the general population. Paola Solis-Pazmino states there is a 65% incidence of thyroid neoplasm in patients with a black thyroid. However, they also say that the finding of a black thyroid only occurs during surgery in patients studied for thyroid nodules. Black pigmentation of the thyroid is not diagnosed by FNA. This means we do not know the exact number of patients with black thyroids, and we cannot accurately know the incidence of thyroid cancer in these patients. In the end, the authors state there is no evidence of increased incidence of thyroid cancer in patients with black thyroids. If this is the truth, there is no justification to do not perform a hemithyroidectomy on a black thyroid. Unfortunately, there is no absolute truth.
Some authors are advising surgical resection of a black thyroid to decrease the risk of papillary thyroid carcinoma. Emad Kandil et al from the Division of Endocrine and Oncologic Surgery from the Tulane University School of Medicine, New Orleans, USA, studied six (6) patients with black thyroids. Pathology diagnosed three (3) papillary cancers, two (2) Hurthle cell neoplasms, and one (1) follicular cancer. FNA had only diagnosed one papillary cancer. The remaining nodules were diagnosed as benign (3) or follicular lesions (2). Is the FNA not accurate in a black thyroid? Is this a take-home message? The authors are not clear, and they could not be. We must remember that all studies include a small number of patients, and we cannot know the true number of patients with black thyroid. If we assume all patients treated with minocycline for a year have a black thyroid, we can eventually estimate the real number. How and when is this going to be done? For now, Emad Kandil advises for a thorough pathological evaluation of a black thyroid and concludes that more studies are needed to find the exact incidence of thyroid cancer associated with a black gland.
Should a black thyroid change your surgical decision? I don't think so.
With the data available, black thyroid should not make us change our preoperative decision of performing a hemithyroidectomy, I think. The risk of RLN injury and severe hypocalcemia following total thyroidectomy is not overtaken by the unknown risk of thyroid cancer associated with black thyroid. Is this the truth? Today it seems to be.
Link to PubMed:
Dr. Carlos Eduardo Costa Almeida
General Surgeon
Comments