Black thyroid: clinical manifestations, ultrastructural findings, and possible mechanisms

The Thyroid Pathologist Meets Therapeutic Pharmacology

The effects of many pharmacological agents on thyroid function are well known. Direct influences on measurements of thyroid function tests are also described. However, certain classes of drugs produce morphological changes in the gland. This review focuses on the significance of the following drug classes for the thyroid pathologist: iodine, antithyroid drugs, psychotropic drugs, antibiotics, cardiotropic drugs, antidiabetic drugs, and immunomodulatory agents. Radioactive iodine initially induces mild histologic changes; however, the long-term effects include marked follicular atrophy, fibrosis, and nuclear atypia-changes that vary depending on the pre-therapy condition of the gland. Some psychotropic drugs have been associated with a spectrum of inflammatory changes throughout the gland. The tetracycline class of antibiotics, namely minocycline, can lead to a grossly black thyroid gland with pigment seen in both colloid and follicular epithelial cells while variably present within thyroid nodules. The surgical pathologist most commonly sees an amiodarone-affected gland removed for hyperthyroidism, and the histologic findings again depend on the pre-therapy condition of the gland. While GLP-1 receptor agonists carry an FDA black box warning for patients with a personal or family history of multiple endocrine neoplasia or medullary thyroid carcinoma, the C cell hyperplasia originally noted in rats has not borne out in human studies. Finally, thyroiditis and hypothyroidism are well known complications of checkpoint inhibitor therapy, and rare cases of severe thyroiditis requiring urgent thyroidectomy have been reported with unique histologic findings. In this review, we describe the histologic findings for these drugs and more, in many cases including their functional consequences.

Minocycline-Induced Scleral and Dermal Hyperpigmentation

PURPOSE

To present a case of minocycline-induced blue scleral pigmentation and discuss the pathophysiology and differential diagnoses. The uses, mechanisms, and other adverse effects of minocycline will also be highlighted.

CASE REPORT

An elderly Caucasian male patient presented for routine ocular examination complaining of blue discoloration to the whites of his eyes. He was found to have bilateral blue scleral pigmentation and blue discoloration to various other dermal areas of his body. The blue pigmentation was also visible in the posterior segment within a scleral crescent around his right optic nerve. This pigmentation was determined to be caused by long-term use of oral minocycline.

CONCLUSIONS

Long-term minocycline use may induce scleral, dermal, and organ hyperpigmentation, typically blue or black in coloration. The pigmentation may reverse with discontinuation of the medication, but can also be permanent. The exact mechanism of pigment deposition remains uncertain, but several theories have been proposed. While the cosmetic appearance may be dramatic, this side effect is not known to cause any systemic or ocular morbidity.

Melanosis tubae: histogenesis and appropriate terminology

We report 2 cases of abnormal localized deposition of lipofuscin-laden macrophages in the lamina propria of the fallopian tube. In both cases there was evidence of ovarian and tubal endometriosis. The authors propose the term "melanosis tubae" (MT) as the most appropriate terminology in the diagnosis of the disease, whose pathogenesis is similar to that occurring in gastrointestinal tract pigmented conditions. The lesion is not of an inflammatory nature so that the term "pseudoxanthomatous salpingitis" is inaccurate and should not be used. Other definitions such as "pseudoxanthomatous salpingiosis," "pigmentosis salpingiosis," "pigmentosis tubae" may be used, but these are descriptive terms that are not suitable for denoting histogenesis. None of the previously reported MT cases showed coexisting tubal endometriosis. Our cases are the first examples of MT associated with tubal endometriosis.

Hyperthyroidism and lupus-like syndrome in an adolescent treated with minocycline for acne vulgaris

Minocycline is a tetracycline antibiotic commonly used in the treatment of acne. While it is generally considered to be a safe medicine, a number of side effects have been associated with its use. We describe an adolescent boy who developed hyperthyroidism and a drug-induced lupus-like syndrome following minocycline treatment for his acne.

Black thyroid revisited: cytologic diagnosis in fine-needle aspirates is unlikely

We report four patients diagnosed with black discoloration of the thyroid gland at surgery and a fifth patient in which the "black thyroid" was an incidental finding at autopsy. The four patients diagnosed at surgery had prior fine-needle aspirations (FNA), which did not reveal any characteristic pigmentation. One patient presented with cervical lymph node metastases from a papillary microcarcinoma of thyroid. The second patient was diagnosed as a cellular adenomatoid nodule, and suppressive therapy was recommended. She elected to have surgery instead. The third patient underwent surgery because of an oxyphilic cell nodule, in a background of lymphocytic thyroiditis, in which a Hürthle cell neoplasm could not be ruled out. His aspirates were reviewed at two other institutions, and no diagnosis of black thyroid was entertained. The fourth patient had an adenomatoid nodule with cystic change and slightly atypical squamous metaplasia. She decided to have surgery, which revealed a black thyroid. Later, it was discovered that the patients had received minocycline for the treatment of acne. FNA does not seem to be a reliable method to diagnose black thyroid preoperatively. Although this is a striking operative finding, diagnosing it on FNA seems to be unlikely and also inconsequential.

[Therapy related alterations to the thyroid gland]

Therapy related alterations to the thyroid gland are associated with more or less specific morphological changes. The therapy (thyrostatic drugs, radio-iodine) may be administered for the treatment of thyroid dysfunction (hyperthyroidism), or the thyroid gland is involved during or after the treatment (irradiation, various drugs) of primarily non-thyroid related diseases. The present review summarizes the most important morphological changes related to therapy.

Black thyroid: report of an autopsy case

A distinctive but very rare side effect of exposure to minocycline is black pigmentation of the thyroid gland. Until 2002, not more than 30 cases of black thyroid had been reported in the English literature. We report on a 24-year-old woman with known antemortem ingestion of minocycline. The woman suffered from a depressive disorder with repeated suicide attempts and committed suicide by a gunshot to the head. At autopsy, the thyroid gland showed coal-black coloration. Upon histology, clumps of black-brown pigment were seen in the colloid, and a granular precipitate of this pigment was noted in the apical portions of the follicular epithelial cells. The diagnosis of minocycline-associated black thyroid was established. Forensic pathological significance of black thyroid may arise from the fact that hypothyroidism has been occasionally associated with minocycline-related black thyroid and that hypothyroidism may contribute to the development of depressive disorders (and thus, in given cases, may be responsible for suicide attempts). Under this assumption, the presence of black thyroid would represent more than just a morphological curiosity in specific cases.

Chromophobe renal cell carcinoma with microcystic and adenomatous arrangement and pigmentation—a diagnostic pitfall. Morphological, immunohistochemical, ultrastructural and molecular genetic report of 20 cases

We present clinical, morphological, immunohistochemical, ultrastructural and molecular genetic features of 20 cases of a peculiar form of chromophobe renal cell carcinoma (CRCC) with morphology differing from that of conventional CRCC. Microscopically, the typical features of the tumors were microcystic arrangement and formation of adenomatous structures. Microcystic areas were composed of smaller eosinophilic and bigger pale cells having cytological appearance typical of conventional CRCC. Cytological features of the adenomatous structures were mostly different from those of conventional CRCC. They had a typical columnar arrangement with nuclei positioned at the base of the glandular structures and a small amount of a deeply eosinophilic cytoplasm often endowed with brush border facing the lumen of the glands. In addition, all the tumors showed a brown pigmentation. The pigmentation was located mostly extracellularly, where it formed pools of heavy deposits. Microscopic calcifications present in all cases formed psammoma bodies or else the calcifications were more extensive and amorphous in shape. Ultrastructurally, the cells showed features characteristic of CRCC: typical cytoplasmic vesicles were 100-700 nm in size and mitochondria had tubulovesicular, lamellar or circular cristae. Some tumor cells contained dark, variously sized electron-dense pigment granules. Neither melanosomes nor membrane-bound neurosecretory granules were seen. Using fluorescence in-situ hybridization probes for chromosomes 1, 2, 6, 10, 13, 17 and 21, the tumors revealed massive loss of tested chromosomes typical for conventional CRCC. Monosomy of chromosomes 1, 2, 6, 10, 13 and 21 was found in 100, 36, 91, 82, 82, 82 and 64% of cases, respectively. None of the cases showed mutation of exons 9, 11, 13 and 17 of the c-kit gene. The important feature of pigmented microcystic chromophobe renal cell carcinoma is a relatively benign biological behavior and the absence of distant metastases and sarcomatoid transformation.

The pigmented "black" neuroendocrine tumor of the pancreas: a question of origin

BACKGROUND

Pigmented neoplasms are extremely rare in the pancreas, and, when black pigment is identified, it often suggests the diagnosis of metastatic melanoma. The authors describe two patients with pigmented "black" neuroendocrine tumors of the pancreas. One patient had an incidental (0.5 cm) finding, and the second patient had a well-demarcated, 4.5-cm mass identified by computerized tomography that was consistent with an islet cell tumor.

METHODS

The two neoplasms were resected surgically and studied by light microscopy using hematoxylin and eosin (H&E), Fontana-Masson, and iron stains. The neoplasms were examined immunohistochemically, and ultrastructural analysis was performed.

RESULTS

H&E stains revealed nests of well-differentiated cells with small, round, centrally placed nuclei. The cytoplasm of the neoplastic cells was pink and granular and contained abundant brown-black pigment. Angiolymphatic and perineural invasion were identified in the larger neoplasm. Both neoplasms demonstrated a positive reaction with a Fontana-Masson stain, which was susceptible to bleaching, and a negative reaction to an iron stain. Immunohistochemical stains showed that neoplastic cells expressed chromogranin and synaptophysin but did not express HMB-45, S-100 protein, glucagon, or insulin. Ultrastructural examination revealed regular neurosecretory granules (100-150 nm) and large, irregularly shaped, electron-dense granules with small lipid inclusions consistent with lipofuscin.

CONCLUSIONS

These pigmented pancreatic neoplasms are similar histologically and radiographically to the "black adenoma" of the adrenal gland. It is important to recognize these tumors, because they may mimic metastatic melanoma.

Melanosis thyroidi

Despite many studies on melanosis thyroidi, there is no consensus concerning the nature of the pigment or its pathogenesis. Here the past literature on this subject is reviewed and results are reported on a case of melanosis thyroidi that provides fresh insight into the nature of the pigment and its genesis. Briefly, the conclusion is that while a few of the pigment granules are classic lipofuscin granules (i.e., single-membrane-bound structures containing electron-dense material in the form of particles, granules and masses, and electron-lucent lipid droplets), a majority of the pigment granules also contain colloid, which is easily identified by its particulate substructure similar to the colloid in the lumen of follicles. Thus, these pigment granules are, in fact, ambilysosomes, where degradation of both endogenous (organelles) and exogenous (colloid) material occurs. Several phagosomes containing colloid were also seen in the thyroid epithelial cells.

Pigmented microcystic chromophobe cell carcinoma: a unique variant of renal cell carcinoma

Five cases of pigmented chromophobe renal cell carcinoma are presented. The patients included four men and one woman between the ages of 60 and 73 years (median age, 66.5 years), who presented with symptoms due to their renal mass. Surgical resection of the renal mass was performed in all patients. Grossly, the tumors were well encapsulated, yellow to dark gray, with a vague nodular pattern on cut surface. The tumors varied between 2.5 and 9 cm in greatest diameter. Histologically, all tumors shared similar features, namely, a malignant cellular proliferation composed of deeply eosinophilic to clear cytoplasm with round nuclei and inconspicuous nucleoli. The cellular proliferation was arranged in a microcystic and/or microalveolar pattern. In one tumor, conventional areas of clear cell carcinoma in association with the chromophobe component were present. In addition, all tumors contained pigmented areas, which were shown by light microscopy to have features of lipochrome pigment. Ultrastructural studies of these areas demonstrated the presence of intracytoplasmic polygonal to round, electron-dense pigment granules, which in some areas seemed to coalesce to form larger granules. In addition, numerous mitochondria and cytoplasmic vesicles were present. The cases described herein highlight an additional morphologic variant of chromophobe renal cell carcinoma.

The lipofuscin-iron association in pigmentosis tubae

Pigmentosis tubae (PT) is a rare condition characterized by the presence of numerous lipofuscin-laden macrophages in the lamina propria of the fallopian tube. Two women, who also had endometriotic ovarian cysts, showed polypoid pigmented tubal mucosae. In addition to lipofuscin, occasional cells showed spotty positivity for iron. Ultrastructural examination of the tubal mucosa showed the lipofuscin-containing bodies, which were similar to lipofuscin-containing lysosomes found in other pigmented conditions. Cytoplasmatic ferritin and hemosiderin in siderosomes were observed in macrophages and endothelial cells of the lamina propria. The present study is the first to demonstrate the presence of iron-containing particles and lipofuscin in the residual bodies of PT. The origin of the excess iron is not clear, but erythrophagocytosis and an abnormal tubal environment could play a role. Iron-promoted lipid peroxidation may alter the lysosomal membranes and contribute to the excessive accumulation of lipofuscin in these cells.

Minocycline-induced intraoral pharmacogenic pigmentation: case reports and review of the literature

Minocycline, a semi-synthetic tetracycline antibiotic, is well documented as being associated with pharmacogenic pigmentation of various tissues in humans and other mammals. The most obvious of these are skin pigmentation, but intraorally include "green" roots of erupted teeth, "black" roots of extracted teeth, a dark stain of the crowns of fully developed teeth, and "black" alveolar bone. This article presents five cases of "black" alveolar bone with photographic documentation of its progress. It also reviews the available English language literature on this phenomenon. The incidence of minocycline staining of alveolar bone is probably 2% of that population taking the drug for 2 months or longer. Presently, minocycline is most widely used in the young adult population for the treatment of acne. With the recent interest in minocycline as a palliative treatment for rheumatiod arthritis, an entirely different population could be experiencing this effect. If minocycline use becomes widespread as a treatment for rheumatoid arthritis, it is likely that more practitioners will be asked to diagnose this sometimes striking, though apparently benign, condition. Recognition of this condition will save the practitioner and the patient from unnecessary concern and surgery.

Follicular Carcinoma Associated with Minocycline-Induced Black Thyroid

Grossly evident black pigmentation of the thyroid has been observed in a number of patients, most of whom have a history of chronic ingestion of minocycline. In the majority of reported cases, no thyroid dysfunction or lesion has been noted, although rare instances of papillary carcinoma have been described. We describe a patient with a history of chronic minocycline ingestion, who presented with a neck mass of recent onset. Histologic examination of the thyroid revealed diffuse pigment deposition, typical for that seen in association with minocycline ingestion. Also present was a 3.2-cm follicular neoplasm with capsular and vascular permeation, consistent with minimally invasive follicular thyroid carcinoma. This represents the first report of follicular carcinoma associated with minocycline-induced black thyroid (MIBT).

Papillary thyroid carcinoma mistaken for malignant melanoma: pitfalls in diagnosis

BACKGROUND

Immunohistochemical methods and aspiration cytology are used with increasing frequency in the diagnosis of head and neck histopathology. Magnetic resonance imaging is also gaining popularity as a diagnostic tool.

METHODS

We report a case of papillary thyroid carcinoma which was initially misdiagnosed as malignant melanoma due to several confounding diagnostic test results.

RESULTS

False-positive immunostaining of a cytologic preparation with a commercial preparation of HMB45 melanoma stain and characteristic MRI findings contributed to the erroneous diagnosis of malignant melanoma.

CONCLUSIONS

Potential pitfalls in test interpretation are discussed, and recommendations for the judicious use of immunostaining, MRI, and other diagnostic studies are presented.

Lipofuscin and abnormalities in colloid in the equine thyroid gland in relation to age

Lipofuscin accumulation and other histological changes in thyroid tissue, previously reported to be age-related, were studied in 31 horses aged up to 35 years. The number of lipofuscin granules relative to thyrocytes increased from birth to 5 years of age. There was a wide individual variation in the number of lipofuscin granules in thyrocytes in mature horses, but this was not directly related to age. Several abnormalities were identified in thyroid colloid. The prevalence of spherites, lipofuscin granules, nucleated cells and shreds of colloid increased with age, but the prevalence of calcium oxalate crystals, erythrocytes, basophilic zones and solid fragments of colloid did not. In horses younger than 7 years, particularly large lipofuscin granules were found in thyrocytes of a small proportion of follicles which also contained abnormal colloid. Such follicles became more common in older horses without being accompanied by large lipofuscin granules. No correlation was found between granule numbers and frequency of colloid abnormalities. These results cast doubt on the traditional assumption that lipofuscin is indigestible cellular residue, since there was little evidence for excretion of granules. It is postulated that lipofuscin in this tissue may be a normal stage in lysosomal catabolism.

Ultrastructural study of a black insulinoma

A case of black insulinoma is reported. The color was due to a cytoplasmic pigment. Immunostaining for neuron-specific enolase and chromogranin was positive in the tumor cells, and the pigment granules themselves reacted with the chromogranin antibody. Numerous beta cell type dense core granules as well as atypical granules were found by electron microscopy. An important finding was that the dense core granules contribute to the lipofuscin pigment formation.

Extensive cutaneous hyperpigmentation caused by minocycline

A 65-year-old man had cutaneous hyperpigmentation that had occurred over the previous 2 1/2 years. The hyperpigmentation was extensive and involved the sclerae, nail beds, and total body; the palms and buttocks were spared. Clinical diagnosis was suggestive of hemochromatosis or heavy metal deposition. Histologic and electron microscopic findings were consistent with lysosomal iron deposition. A careful history showed that minocycline was the cause. Its use was discontinued, and after several years the patient's pigmentation is gradually returning to normal.

Black thyroid: a pitfall for aspiration cytology

Black thyroid discoloration following long-standing use of minocycline has been reported. Morphologic findings of aspiration cytology of these lesions was first reported from The Ohio State University. This abstract describes a second case of black thyroid that was preceded by aspiration cytology. In both cases, thyroidectomies were performed based on "indeterminate" fine-needle aspiration cytology (FNAC). Degenerative changes in follicular epithelial cells in black thyroid causes nuclear hyperchromasia and chromatin clumping, which may be mistaken for neoplasia. Pigment present in follicular epithelial cells and macrophages may be obscured by pigments with similar microscopic appearances, such as hemosiderin. A clinical history of the chronic use of a tetracycline derivative should alert the pathologist to the possibility of black thyroid. Diagnosis may be made by applying special stains on the cell block. The pigment stains with Melanin stain (Fontana) and bleaches with potassium permanganate. In the light of increasing use of FNAC of the thyroid gland and the large number of patients who received tetracycline therapy in the last two decades, it is likely that some practicing cytopathologists may experience this pitfall.

Melanin production in black medullary thyroid carcinoma (MTC)

Melanin production by two medullary carcinomas of the thyroid is reported and discussed. In both tumours, melanin and calcitonin could be detected in the same cells.

"Black thyroid" associated with minocycline therapy. A report of an autopsy case and review of the literature

An autopsy case of a 69-year-old woman showing black discoloration of the thyroid gland designated as "Black thyroid" was reported. The patient received long-term, high dose antibiotics minocycline therapy (total dose: 70 g) for bronchial asthma associated with respiratory infection and died of uterine cancer. The thyroid gland was coal black in color and histological examination revealed numerous dark brown pigments scattered in the follicular epithelium and colloid matrix. Special stains and electron microscopic examination suggested these deposited pigments to be consistent with lipofuscin. Histological examination of the thyroid glands in consecutive 500 autopsy cases revealed intimate relationship between deposition of lipofuscin pigments in the follicular epithelium and age of the patients. But, massive deposition of lipofuscin in the thyroid alone did not make the thyroid black and addition of minocycline appeared to be necessary for the black discoloration.