Thyroid paraganglioma. Report of 3 cases and description of an immunohistochemical profile useful in the differential diagnosis with medullary thyroid carcinoma, based on complementary DNA array results

Histopathology of C Cells and Medullary Thyroid Carcinoma

C cells are the neuroendocrine cell component of the thyroid gland that embryologically arise from the pharyngeal endoderm. Normal C cells are concentrated in the upper two-thirds of both lateral lobes, appear singly or in small groups dispersed in, among or peripherally to the follicles, and are involved in the production of calcitonin. Reactive C-cell hyperplasia should be differentiated from proliferation of atypical C cells (neoplastic C-cell hyperplasia) which is considered an intraepithelial neoplasia of C cells/medullary carcinoma in situ, a precursor lesion associated to familial medullary thyroid carcinoma (MTC). MTC typically exhibits a lobular and/or trabecular growth pattern with amyloid deposits; however, due to its great histological variability, immunohistochemical positivity for calcitonin, carcinoembryonic antigen, calcitonin-gene-related peptide, insulinoma-associated protein 1, and/or other markers is necessary to confirm diagnosis. Investigation of germline RET proto-oncogene mutation is mandatory to identify familial MTC. Somatic RET mutations or fusions as well as RAS mutations in cytological and/or biopsy samples may represent therapeutic targets. Mixed medullary and follicular-derived cell carcinoma is a heterogeneous group of tumors which needs to be distinguished from collision tumors.

Paragangliomas and Anemia: Literature Review and Case Report

Paragangliomas are rare neuroendocrine tumors that arise from the extra-adrenal autonomic paraganglia, i.e., small organs consisting mainly of neuroendocrine cells that are derived from the embryonic neural crest and have the ability to secrete catecholamines. Paragangliomas can derive from either parasympathetic or sympathetic paraganglia. Most of the parasympathetic ganglia-derived paragangliomas are nonfunctional, and symptoms result from mass effect. Conversely, the sympathetic paragangliomas are functional and produce catecholamine. Although such patients could have symptoms similar to pheochromocytoma, mass effect symptoms, or non-specific symptoms, being benign tumors, they can also present with anemia, specifically iron-deficiency anemia. Considering that neoplastic pathology is chronically accompanied by moderate, normochromic, normocytic anemia, association between paragangliomas that are mostly benign but with a potential degree of malignancy and anemia is not as frequent as expected, with only 12 cases reported in the literature. We report a case of a 54-year-old female patient diagnosed with a paraganglioma of the carotid glomus accompanied by severe normochromic, normocytic anemia, which reached normal limits after excision of the paraganglioma.

Thyroid paraganglioma accompanied by lymph node metastasis or trachea invasion: A case report

Thyroid paraganglioma (TP) is an uncommon neuroendocrine tumor with potential for misdiagnosis. Case 1 (male; 44 years old) presented with hoarseness for 3 months. A 2.5-cm gray nodule in the left thyroid was diagnosed as TP by immunohistochemistry. Lymph node metastasis was confirmed by H&E staining and immunohistochemistry. The patient was followed-up for 3 years without any signs of recurrence or metastasis. Case 2 (female; 39 years old) presented with an asymptomatic but rapidly growing thyroid nodule. The patient underwent thyroidectomy 8 years ago (2008) and was diagnosed with TP postoperatively. The patient was diagnosed with recurrence and exhibited trachea invasion. Thyroidectomy and partial trachea resection were performed. A literature review revealed that 62 other cases of TP have been reported, and most of them exhibited low malignant potential. However, the two cases presented in the current case report exhibited a high malignant potential, accompanied by lymph node metastasis or trachea invasion, and these features imply that the choice of treatment for patients should be based on their different degrees of malignancy.

Paraganglioma-like medullary thyroid carcinoma: A case report and literature review

Medullary thyroid carcinoma (MTC) accounts for 3%-5% of all thyroid malignancies. Most MTC can be diagnosed by their typical cytologic and histologic morphology and immunohistochemical features. However, some rare variants of MTC may pose diagnostic difficulties on both cytology and histology. Paraganglioma-like MTC (PLMTC) is a rare, but widely recognized variant of MTC. PLMTC is known to share morphological and architectural similarities with paraganglioma, hyalinizing trabecular tumor, and carcinomas of thyroid follicular cell origin, such as follicular carcinoma and follicular variant of papillary thyroid carcinoma. The combination of clinicopathologic features and a battery of immunohistochemical markers is essential for making a correct diagnosis. Herein, we report one case of PLMTC with both cytologic and histologic features and review the clinicopathologic features of previously reported cases.

Thyroid Paraganglioma: Our Experience and Systematic Review of the Literature on a Rare Tumor

INTRODUCTION

Primary paraganglioma (PG) of the thyroid gland is an extremely rare neuroendocrine tumor with potential for misdiagnosis. We describe 2 cases of thyroid PG, suggest a possible diagnostic and therapeutic management strategy, and present a systematic review of the literature.

CASE REPORTS

Two 67-year-old women presented similarly with asymptomatic but rapidly growing thyroid nodules in which malignancy was suspected after fine needle aspiration biopsy, "THY 4" according to the 2014 SIAPEC classification, both undergoing total thyroidectomy. Unexpectedly, immunohistochemistry showed neuroendocrine cellular architecture that was negative for common markers of well-differentiated follicular neoplasms, thyroglobulin, thyroid transcription factor 1, cytokeratins and medullary thyroid cancer, calcitonin, carcinoembryonic antigen, whereas neuron-specific enolase, synaptophysin, chromogranin A, and S-100 protein were highly expressed, confirming the diagnosis of primary thyroid PG. The patients were both discharged on postoperative day 2, without any other therapy and are currently well without evidence of local recurrence of metastatic disease, after 4 years and 3 months of follow-up, respectively.

DISCUSSION

These are the only 2 cases of thyroid PG experienced in our center which specializes in thyroid surgery. Thyroid PG is a rare neuroendocrine neoplasm first described by Van Miert in 1964 with just over 50 cases reported in the literature. Our experience is concordant with the literature that the diagnosis of the primary PG of the thyroid is challenging, due to its low prevalence and the cytologic and histopathologic similarities with other more frequently diagnosed benign and malignant thyroid tumors. Immunohistochemistry is required for definitive diagnosis but gross tumor characteristics are also helpful for diagnosis. Surgical resection is the recommended standard treatment.

The Diagnosis and Clinical Significance of Paragangliomas in Unusual Locations

Paragangliomas are neuroendocrine neoplasms, derived from paraganglia of the sympathetic and parasympathetic nervous systems. They are most commonly identified in the head and neck, being most frequent in the carotid body, followed by jugulotympanic paraganglia, vagal nerve and ganglion nodosum, as well as laryngeal paraganglia. Abdominal sites include the well-known urinary bladder tumors that originate in the Organ of Zuckerkandl. However, other unusual sites of origin include peri-adrenal, para-aortic, inter-aortocaval, and paracaval retroperitoneal sites, as well as tumors in organs where they may not be expected in the differential diagnosis of neuroendocrine neoplasms, such as thyroid, parathyroid, pituitary, gut, pancreas, liver, mesentery, lung, heart and mediastinum. The distinction of these lesions from epithelial neuroendocrine neoplasms is critical for several reasons. Firstly, the determination of clinical and biochemical features is different from that used for epithelial neuroendocrine tumors. Secondly, the genetic implications are different, since paragangliomas/pheochromocytomas have the highest rate of germline susceptibility at almost 40%. Finally, the characterization of metastatic disease is unique in these highly syndromic lesions. In this review, we summarize updated concepts by outlining the spectrum of anatomic locations of paragangliomas, the importance of morphology in establishing the correct diagnosis, the clinical implications for management, and the impact of genetics on the distinction between multifocal primary tumors compared with malignant disease.

Paradoxical hypertension

Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiological syndrome characterized by white matter vasogenic edema affecting the posterior occipital and parietal lobes of the brain predominantly. A 48-year-old female patient presented to ER with complaints of breathlessness and developed sudden painless loss of vision while eliciting history. The patient had a heart rate of 104/min and accelerated hypertension (BP of 220/120 mm of Hg). MRI Brain showed subcortical white matter T2/Fluid-attenuated inversion recovery hyperintensities, suggestive of PRES. The patient regained vision completely over 5 days after nitroglycerin infusion and calcium channel blockers. Beta blocker was started in view of increased BP and anxiety. Blood pressure paradoxically increased from 170/90 mm of Hg to 200/100 mm of Hg. Urine and plasma metanephrines were elevated. Contrast-enhanced computerized tomography abdomen showed locally infiltrative, retroperitoneal mass in left para-aortic prevertebral region diagnosed as paraganglioma. The patient improved with alpha blockers and surgical removal of paraganglioma. 0.1% of hypertensive patients harbor a pheochromocytoma or paraganglioma and its presentation as PRES is very rare.

Immunohistochemical Biomarkers in Thyroid Pathology

The application of immunohistochemistry to the diagnosis of thyroid lesions has increased as new biomarkers have emerged. In this review, we discuss the biomarkers that are critical for accurate diagnosis, prognosis, and management. Immunohistochemical markers are used to confirm that an unusual tumor in the thyroid is indeed of thyroid origin, either of follicular epithelial or C-cell differentiation; the various mimics include nonthyroidal lesions such as parathyroid tumors, paragangliomas, thymic neoplasms, and metastatic malignancies. Tumors of thyroid follicular epithelial cells can be further subclassified using a number of immunohistochemical biomarkers that can distinguish follicular-derived from C-cell lesions and others that support malignancy in borderline cases. The use of mutation-specific antibodies can distinguish papillary carcinomas harboring a BRAF^V600E mutation from RAS-like neoplasms. Immunostains have been developed to further identify molecular alterations underlying tumor development, including some rearrangements. Altered expression of several biomarkers that are known to be epigenetically modified in thyroid cancer can be used to assist in predicting more aggressive behavior such as a propensity to develop locoregional lymphatic spread. Immunohistochemistry can assist in identifying lymphatic and vascular invasion. Biomarkers can be applied to determine dedifferentiation and to further classify poorly differentiated and anaplastic carcinomas. The rare tumors associated with genetic predisposition to endocrine neoplasia can also be identified using some immunohistochemical stains. The application of these ancillary tools allows more accurate diagnosis and better understanding of pathogenesis while improving prediction and prognosis for patients with thyroid neoplasms.

Primary Melanotic Paraganglioma of Thyroid Gland: Report of a Rare Case With Clinicopathologic and Immunohistochemical Analysis and a Literature Review

Background:

Pigmented paraganglioma is a special type of paraganglioma, and it is rare in the thyroid.

Case Presentation:

We report a case of a 41-year-old woman who had complained of a mass in the thyroid gland. Histology revealed tumor cells arranged in a nest-like or organoid pattern, separated by delicate fibrovascular septa. Two distinct components were observed. In the first, which constituted the majority of the tumor cells, no pigments were observed. In the second, a few cells with pigment showed intercellular substance, but the structure was unclear. Using immunohistochemistry, cells in the first component were confirmed to be diffuse strong positive for synaptophysin, but negative for chromogranin A, pan-cytokeratin, calcitonin, and thyroglobulin. About 1% of tumor cells were stained by Ki-67. In the margins of the tumor, a few cells were observed to be positive for HMB-45 and Melan A after bleaching by oxalic acid. The stromal cells were positive for S-100. Using electron microscopy, a few cells containing many round melanin bodies with greater electron density granules of nonuniform size were observed. The diagnosis of primary melanotic paraganglioma of the thyroid gland was made.

Conclusion:

Primary melanotic paraganglioma of the thyroid gland is a rare, low malignant potential tumor. To the best of our knowledge, this is the first case described.

The Management of Locally Invasive Primary Thyroid Paraganglioma: A Case Report and Review of the Literature

Paragangliomas (PG) are very rare neuroendocrine tumours, arising from neural crest derived paraganglia of the autonomic nervous system. Primary thyroid paraganglioma (PTPG) is a rare site of PG and only 45 cases have been previously reported. The preoperative diagnosis of PTPGs presents a challenge as the clinical, cytological and histological features overlap with more common primary thyroid cancers. A 55 year old male was found to have significant enlargement of the left lobe of his thyroid. Following lobectomy, the thyroid lobe showed unencapsulated tumour which was positive for synaptophysin, CD56 and S100 (sustentacular cells). Post-operative imaging demonstrated incomplete resection. There was no post-operative radiotherapy and monitoring was by 6-12 monthly MRI. 48 months after his surgery he is alive and well with no evidence of disease progression. The diagnosis of PTPG was only made postoperatively, and although rare should be considered in the differential diagnosis of a hypervascular thyroid nodule.

A registry-based study of thyroid paraganglioma: histological and genetic characteristics

The precise diagnosis of thyroid neoplasias will guide surgical management. Primary thyroid paraganglioma has been rarely reported. Data on prevalence, immunohistochemistry (IHC), and molecular genetics in a systematic series of such patients are pending. We performed a multinational population-based study on thyroid paraganglioma and analyzed prevalence, IHC, and molecular genetics. Patients with thyroid paraganglioma were recruited from the European-American-Head-and-Neck-Paraganglioma-Registry. Demographic and clinical data were registered. Histopathology and IHC were re-investigated. All patients with thyroid paraganglioma underwent molecular genetic analyses of the SDHA, SDHB, SDHC, SDHD, SDHAF2, VHL, RET, TMEM127, and MAX genes. Analyses included Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) for detection of large rearrangements. Of 947 registrants, eight candidates were initially identified. After immunohistochemical analyses of these eight subjects, 5 (0.5%) were confirmed to have thyroid paraganglioma. IHC was positive for chromogranin, synaptophysin, and S-100 and negative for calcitonin in all five thyroid paragangliomas, whereas the three excluded candidate tumors stained positive for pan-cytokeratin, a marker excluding endocrine tumors. Germline variants, probably representing mutations, were found in four of the five confirmed thyroid paraganglioma cases, two each in SDHA and SDHB, whereas the excluded cases had no mutations in the tested genes. Thyroid paraganglioma is a finite entity, which must be differentiated from medullary thyroid carcinoma, because medical, surgical, and genetic management for each is different. Notably, approximately 80% of thyroid paragangliomas are associated with germline variants, with implications for additional tumors and a potential risk for the family. As opposed to sporadic tumors, surgical management and extent of resection are different for heritable tumors, each guided by the precise gene involved.

Medullary thyroid carcinoma: a 25-year perspective

This article summarizes the major clinical, pathological, and molecular features of medullary thyroid carcinoma (MTC), based on a review of the most significant advances in our understanding of this tumor type over the last 25 years. MTC is a neuroendocrine carcinoma that shows evidence of C-cell differentiation. The tumor has a distinctive morphologic appearance, including the presence of amyloid deposits. Immunostaining for calcitonin, carcinoembryonic antigen, calcitonin gene-related peptide, and thyroid transcription factor 1 is helpful in differential diagnosis. Identification of RET mutations in familial and sporadic MTC has brought important changes in early diagnosis and treatment. Surgery remains the cornerstone of effective therapy. Understanding the molecular basis of MTC will allow identification of novel approaches for individualized treatment.

Paragangliomas: update on differential diagnostic considerations, composite tumors, and recent genetic developments

Recent developments in molecular genetics have expanded the spectrum of disorders associated with pheochromocytomas (PCCs) and extra-adrenal paragangliomas (PGLs) and have increased the roles of pathologists in helping to guide patient care. At least 30% of these tumors are now known to be hereditary, and germline mutations of at least 10 genes are known to cause the tumors to develop. Genotype-phenotype correlations have been identified, including differences in tumor distribution, catecholamine production, and risk of metastasis, and types of tumors not previously associated with PCC/PGL are now considered in the spectrum of hereditary disease. Important new findings are that mutations of succinate dehydrogenase genes SDHA, SDHB, SDHC, SDHD, and SDHAF2 (collectively "SDHx") are responsible for a large percentage of hereditary PCC/PGL and that SDHB mutations are strongly correlated with extra-adrenal tumor location, metastasis, and poor prognosis. Further, gastrointestinal stromal tumors and renal tumors are now associated with SDHx mutations. A PCC or PGL caused by any of the hereditary susceptibility genes can present as a solitary, apparently sporadic, tumor, and substantial numbers of patients presenting with apparently sporadic tumors harbor occult germline mutations of susceptibility genes. Current roles of pathologists are differential diagnosis of primary tumors and metastases, identification of clues to occult hereditary disease, and triaging of patients for optimal genetic testing by immunohistochemical staining of tumor tissue for the loss of SDHB and SDHA protein. Diagnostic pitfalls are posed by morphological variants of PCC/PGL, unusual anatomic sites of occurrence, and coexisting neuroendocrine tumors of other types in some hereditary syndromes. These pitfalls can be avoided by judicious use of appropriate immunohistochemical stains. Aside from loss of staining for SDHB, criteria for predicting risk of metastasis are still controversial, and "malignancy" is diagnosed only after metastases have occurred. All PCCs/PGLs are considered to pose some risk of metastasis, and long-term follow-up is advised.

Primary paraganglioma of thyroid gland: a clinicopathologic and immunohistochemical analysis of three cases with a review of the literature

Thyroid paraganglioma is an extremely rare tumor and frequently mistaken for other thyroid neoplasms. Increased awareness of its potential presentation in thyroid and its characteristic features is essential for avoiding diagnostic and therapeutic pitfalls. We describe here three additional cases of primary thyroid paraganglioma and analyze their clinical findings and pathological characteristics. Patients included two women and one man presenting with asymptomatic thyroid nodules. Radiological examinations were nonspecific and none had been diagnosed correctly before surgery. On intraoperative frozen section consultation they were all misdiagnosed as carcinomas, either primary or metastatic. However, the permanent sections showed features consistent with paraganglioma. Of note, two cases displayed extension into adjacent thyroid tissues, one of which exhibited increased mitotic activity, confluent tumor necrosis and vascular invasion. Immunohistochemically, the neoplastic chief cells expressed chromogranin, synaptophysin, neuron-specific enolase and CD56, whereas the sustentacular cells were highlighted by S100 protein. All three patients were well with normal hormone secretion, without local recurrence or distant metastasis at last follow-up (range 10-47 months). We further reviewed the literature to summarize the characteristics of this distinctive entity. Albeit being very rare, paraganglioma should be included in the differential diagnosis of hypervascular thyroidal neoplasms. Accurate diagnosis relies on the histopathogical findings and adjunctive immunohistochemcial studies. To date, all the reported cases have pursued a benign course. Although atypical features seem to have no association with clinical behavior, long time postoperative surveillance with biochemical screening of hormone secretion, cervical ultrasonography and whole-body CT scan is recommended.