Non-chromaffin paragangliomatosis manifesting as a cold thyroid nodule

Pitfalls in the management of subglottic paragangliomas at unusual location: a case report and literature review

Background

Subglottic paragangliomas (PGs) are exceptionally rare and unpredictable, occasionally presenting at an atypical location. There are three different clinical forms of subglottic PGs: intraluminal (tracheal PGs), extraluminal (thyroid PGs) and the mixed type (both intraluminal and extraluminal, mixed-subglottic PGs). These tumors are usually misdiagnosed as other relatively common primary thyroid or laryngotracheal tumors, and the treatment is troublesome.

Case presentation

A 22-year-old male patient with subglottic PGs has been successively misdiagnosed as thyroid tumors and subglottic hemangiomas, and lastly underwent local extended lumpectomy and laryngotracheal reconstruction with a pedicled thoracoacromial artery perforator flap (PTAPF). The patient was decannulated successfully after the second-stage tracheal reconstruction with a local flap, and no evidence of local recurrence and distant metastasis of the tumor until now.

Conclusion

Subglottic PGs can be easily misdiagnosed as laryngotracheal or thyroid tumors when presented at an atypical location. It is essential for otolaryngologists and head and neck surgeons to remain vigilant against these tumors. If the tumor is not diagnosed or removed completely, patients may encounter a risk of lethal paroxysm, which is incredibly troublesome.

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.

Primary Paraganglioma of the Thyroid Gland: Clinical and Immunohistological Analysis with a Literature Review

Primary paraganglioma of the thyroid is a rare neuroendocrine tumour, often mistaken for other thyroid neoplasms. Here, we describe a case of initially misdiagnosed primary paraganglioma of the thyroid and study its clinical presentation, management, investigation, and immunohistological findings. A 72-year-old male presented with a left-sided solitary thyroid lobe and isthmus nodule. Ultrasound, fine needle aspiration, and computed tomography did not provide a clear diagnosis and subsequently, a left lobectomy and isthmusectomy were performed. The initial histopathological findings of the tumour revealed positivity to chromogranin and calcitonin, suggesting a medullary carcinoma replacing the left lobe of the thyroid. In a second histopathological review at an external laboratory, the tumour cells showed positive focal staining for chromogranin, but were negative for both calcitonin and monoclonal carcinoembryonic antigen, suggesting thyroid paraganglioma. This case highlights the importance of accurate histopathological diagnosis and the need to be aware of the possibility of thyroid paraganglioma initially presenting as a thyroid nodule.

Thyroid Paraganglioma: "Naked" Nuclei as a Clue to Diagnosis on Imprint Cytology

A cytologic diagnosis of paraganglioma of the thyroid is difficult to make because the thyroid gland is an unusual location for such a tumor and the cytologic findings overlap with other benign and malignant thyroid tumors. We report the case of a 28-year-old female presenting with a solitary mass of the right thyroid gland. A diagnosis of paraganglioma was made on the resected specimen. At the time of tumor resection, imprint cytology was performed. The imprint was hypercellular with cohesive sheets of round cells showing anisokaryosis and anisocytosis. Moreover, there was a second cell type consisting of oval nuclei with dispersed nuclear chromatin present within the sheets and separate as "naked" nuclei. By immunohistochemistry, the cohesive round cells were positive for chromogranin A, indicating chief cells. The naked nuclei were positive for S-100 protein, indicating sustentacular cells. To the best our knowledge, this is the first case report describing naked nuclei as a cytologic feature of paraganglioma. Identification of sustentacular cells provides a clue for the cytologic diagnosis of paraganglioma.

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.

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.

Thyroid-associated paragangliomas

BACKGROUND

Paragangliomas in the region of the thyroid gland are rare tumors that can present a diagnostic challenge by mimicking follicular and c-cell derived thyroid tumors.

SUMMARY

Thyroid-associated paragangliomas are likely a subset of laryngeal paragangliomas and, although quite rare, should be considered in the differential diagnosis of a hypervascular thyroid nodule. The preoperative diagnosis of thyroid-associated paragangliomas can be challenging since the cytologic and histologic features overlap with more common primary thyroid neoplasms, in particular medullary carcinoma. Differential expression of a panel of immunohistochemical markers, including neuro-specific enolase, chromogranin A, synaptophysin, keratin, and S100, can be used to distinguish thyroid-associated paragangliomas from primary thyroid tumors. Intraoperatively, thyroid-associated paragangliomas may be associated with significant intraoperative bleeding and are often densely adherent to surrounding tissues, including the recurrent laryngeal nerve. Interestingly, the aggressive local behavior of these tumors does not correspond to potential for malignancy, as there are no patients with malignant thyroid-associated paragangliomas reported in the medical literature. Therefore, these tumors may be treated with limited resection. Postoperatively, patients with paragangliomas should receive hormonal evaluation for functional disease, imaging evaluation for multicentric and metastatic disease, and genetic counseling.

CONCLUSION

Thyroid-associated paragangliomas are an important part of the differential diagnosis of a hypervascular thyroid nodule, especially in a patient with a fine-needle aspiration biopsy suggestive of medullary thyroid carcinoma, but with unremarkable serum calcitonin levels. Consideration of a thyroid-associated paraganglioma also has important operative and postoperative implications for determining the extent of thyroid resection as well as follow-up testing.

Primary thyroid paraganglioma presenting with double thyroid nodule: a case report

Paragangliomas (PGs) are exceptionally rare tumors. Only 24 cases have previously been reported. Both preoperative and postoperative differential diagnosis is very difficult. Due to interesting nature in diagnosis and differential diagnosis, we describe the case 58-year-old euthyroid woman with a thyroid PG. The patient had presented with euthyroid multinodular goiter to a secondary hospital. The patient was treated with right lobectomy, isthmectomy, and left partial lobectomy without any imaging procedures. No complication had been developed during and following the operation. Initial pathological examination suggested medullar thyroid carcinoma (MTC) in a nodule of 4.5 cm in diameter on right thyroid lobe and a nodule of 2.5 cm in diameter on the left thyroid lobe without amyloid stroma and referred to our third-stage hospital. Repeated pathological examination involving immunohistochemistry revealed that the tumor was stained positively to neuron-specific enolase, chromogranin A, synaptophysin, and S-100 protein. No immunoreactivity was detected against thyroglobulin, calcitonin, parathormone, carcino-embryonic antigen, thyroid transcription factor-1, and cytokeratin. A diagnosis of thyroid PG was finally made. Laboratory analyses and imaging procedures excluded any neck or extracervical tissues metastasis or multiple endocrine neoplasia. In conclusion, thyroid PG is an elusive tumor. We present this interesting nature thyroid PG case to highlight importance of careful evaluation of clinical and pathological findings to correctly identify paragangliomas which anatomically mimic MTCs. This report is the first case of thyroid PG presenting with multinodular goiter in the literature.

Primary paraganglioma of the thyroid gland

We describe the case of a 46-yr-old euthyroid woman, who was submitted to right lobectomy plus isthmusectomy because of a 30 mm large, rapidly growing thyroid nodule. Two cytological examinations of fine needle aspiration biopsy (FNAB) specimens were not diagnostic. Histology showed a neoplasm composed of nests of chief cells, almost completely replacing thyroid parenchyma, infiltrating the capsule and surgical resection margins, and invading perithyroid tissues. Immunohistochemical analysis revealed that the tumor stained positively to chromogranin, synaptophysin, NSE, S-100 protein and tyrosine hydroxylase, whereas no immunoreactivity was detected against cytokeratin, thyroglobulin, TTF-1, calcitonin and CEA. A diagnosis of thyroid paraganglioma (PG) was finally made. No complications developed following operation. Laboratory analysis and imaging study excluded multicentric disease, metastases to neck or extracervical organs, and multiple endocrine neoplasia (MEN). We report this unusual case, underscore its clinical and immunohistochemical features and discuss differential diagnosis.

Relapsing paraganglioma of the inferior laryngeal paraganglion: case report and review of the literature

BACKGROUND

Laryngeal paragangliomas are very rare neoplasms derived from the superior or inferior laryngeal paraganglia. The paragangliomas of the inferior laryngeal paraganglion, depending on their anatomic variability, can give rise to two different clinical expressions of the same process, namely the so-called thyroid paragangliomas and the inferior laryngeal or subglottic paragangliomas.

METHODS

We present a case for which we have not found any previous descriptions of a cervical and subglottictracheal relapse of a thyroid paraganglioma removed 3 years earlier. We review the literature.

RESULTS

We have found a total of 22 paragangliomas of the inferior laryngeal paraganglia, 23 including our case.

CONCLUSIONS

Thyroid paragangliomas and inferior laryngeal or subglottic paragangliomas should be included under the term "paragangliomas" of the inferior laryngeal paraganglion. These tumors are slow growing, benign, hypervascular, and much more common in middle-aged women. Immunohistochemistry is essential for its diagnosis. Open, conservative surgery is the treatment of choice.

Paraganglioma of the thyroid: two cases that clarify and expand the clinical spectrum

BACKGROUND

Paragangliomas (PGs) can, on rare occasions, arise within the thyroid parenchyma presumably from displaced laryngeal paraganglia. On the basis of a limited number of reported cases, thyroid PGs invariably affect women, they are always benign, and they are usually mistaken for some other more common thyroid lesion.

METHODS

We describe the histopathologic features, immunohistochemical findings, and clinical characteristics of two thyroid PGs.

RESULTS

One tumor was incidentally discovered in a 55-year-old man during evaluation of a carotid bruit. The other tumor aggressively invaded the trachea and esophagus of a 52-year-old woman with a presumed long-standing nodular goiter. In both cases, the initial pathologic evaluation suggested medullary thyroid carcinoma. Both patients are alive without recurrent disease after surgical resection.

CONCLUSIONS

These cases emphasize the need to consider PG in the differential diagnosis of neuroendocrine thyroid tumors, even in those tumors involving men or behaving in a locally aggressive fashion. Failure to do so carries grave implications regarding patient prognosis and management.

Primary intrathyroidal paraganglioma with metachronous carotid body tumor: report of a case and review of the literature

A case of primary intrathyroidal paraganglioma is reported, and the light microscopic and immunohistochemical findings are described. Primary paragangliomas of the thyroid region are extremely uncommon and are therefore often confused clinically and histopathologically with more common intrathyroidal mass lesions. The diagnostic difficulties are underscored by the present case, which was misdiagnosed twice, firstly as a medullary thyroid carcinoma and secondly as a follicular thyroid carcinoma. Immunohistochemistry may be very helpful in arriving at the correct diagnosis. The case was further complicated by a second neck mass contralateral to the original thyroid nodule, which was interpreted as consistent with metastasis. The second lesions was proved angiographically and histologically to be a carotid body paraganglioma.

Thyroid paraganglioma: a clinicopathologic and immunohistochemical study of three cases

We report three cases of intrathyroidal paraganglioma. The patients were adult women without significant personal or family histories that presented with an asymptomatic thyroid nodule. The tumors were single, well-circumscribed solid masses, 2 cm in greatest diameter, located within one thyroid lobe. Microscopically, they were encapsulated and showed the typical nesting (Zellballen) pattern of paraganglioma in other sites. Two of the tumors were composed of small- to medium-sized cells with granular amphophilic cytoplasm, and the third consisted of relatively large cells having a similar staining quality. Immunohistochemically, all tumors showed positivity for neuron-specific enolase, chromogranin A, and synaptophysin. S-100 protein-positive sustentacular cells were demonstrated in each case. Negative staining for epithelial markers, thyroglobulin, carcinoembryonic antigen, calcitonin, calcitonin gene-related peptide, serotonin, vimentin, and Congo red excluded other tumors that were considered in the differential diagnosis, such as medullary carcinoma, hyalinizing trabecular adenoma, atypical follicular adenoma, Hurthle-cell neoplasm, and metastatic carcinoid tumor. The patients were alive and well without evidence of recurrent disease at the time of the last follow-up. The previous literature on these tumors is discussed. We conclude that intrathyroidal paraganglioma exists and that this tumor can be distinguished from other similar-appearing neoplasms in this organ.

Paragangliomas of the carotid bifurcation: oncological aspects of vascular surgery

The present study reviews in concise form the past 12 years of our clinical experience with paragangliomas of the carotid body. Every aspect of the anatomical, histological and biological and biological behaviour of paragangliomas of the carotid body has been recorded in order to be able to define better surgical management and the clinical prognosis. In addition to the conventional histological methods of investigation we also applied immunohistochemistry and made use of electron microscopy. Eighteen tumours of the carotid body in 12 female and four male patients with a mean age of 54 years (34 to 70 years) were treated surgically. Angiography of the aortic arch and supra-aortic branches was undertaken diagnostically in every case. In three patients computer tomography and magnetic resonance imaging demonstrated spreading of the tumour up to the base of the skull and pre-operative embolization of the arteries supplying the tumour was performed to decrease tumour vascularity. In four cases (22%) resection of the internal carotid artery and its reconstruction by a saphenous vein graft was required in order to achieve the therapeutic aim of a complete extirpation of tumourous tissue and preserving the vascular system of the internal carotid artery. In three cases (16%) there was histological evidence of a metastasizing process to the local lymph nodes of the neck and, due to this criterion of malignancy, 50-60 Gy of radiation was applied to the site of the tumour after surgery. Four patients experienced a transient neurological deficit in the supply area of the hypoglossal and the recurrent nerves. In one case, the vagus nerve could not be retained. In an average follow-up of 102 months we recorded one case of local recurrence 13 months after the initial resection and radiation treatment applied to a malignant paraganglioma. All the other patients were doing well without evidence of recurrent disease.

Paraganglioma: an unusual tumour of the parathyroid gland

A case of paraganglioma arising within a parathyroid gland is reported. The lesion was an incidental finding in a block dissection of neck performed for squamous carcinoma of the pharynx. A well-circumscribed lesion, exhibiting the characteristic pathological features of a paraganglioma, was embedded within the right inferior parathyroid gland. Due to its location, the chief histological differential diagnosis was an unusual variant of parathyroid adenoma. Immunohistochemistry and electron microscopy assisted in reaching a diagnosis. This, as far as we are aware, is the first reported case of a paraganglioma of the parathyroid gland.

Thyroid paraganglioma

Paraganglioma of the thyroid gland is a rare neoplasm. Only eight cases have previously been reported. The neoplasm was confined to the thyroid in all but two patients; laryngeal involvement was seen in one and tracheal involvement in another. A review of these previously reported cases is presented along with the details of an additional case with laryngeal involvement. Laryngeal and thyroid paragangliomas are compared and contrasted. The anatomic and embryologic basis of these tumors and the diagnosis and treatment are discussed. We suggest changing the nomenclature and reporting of these lesions on the basis of their apparent common origin. Surgery remains the treatment of choice in most paragangliomas, including those involving the larynx and thyroid. Although the number of reported cases is small, there have been no cases of distant metastases or local recurrence after adequate surgical removal.

Paragangliomas of the head and neck. Immunohistochemical analysis of 16 cases in comparison with neuro-endocrine carcinomas

Sixteen cases of paragangliomas of the head and neck including 8 of the vagal body, 3 of the carotid body, 2 jugulotympanic, 2 vagal or jugulotympanic and 1 of the larynx were analysed. Clinically, 13 tumors were benign, 2 showed local aggressivity and 1 showed metastases. All tumors were tested with antisera directed against neuron-specific enolase (NSE), chromogranin A (CGA), S-100 protein, neurofilaments (NF), glial fibrillary acid protein (GFAP) and cytokeratin (CK). Immunohistochemical results were compared with those of 5 cases of neuroendocrine carcinoma (NC) (1 of the oral vestibule, 1 of the larynx, 1 Merkel-cell tumor of the skin and 2 medullary thyroid carcinomas). Immunoreactivity for NSE and/or CGA was always positive in all paragangliomas and NC. S-100 protein was positive in sustenticular cells in all cases of paragangliomas and focally in two cases of NC. NF and GFAP were focally positive in 3 and 2 paragangliomas respectively; and in 1 NC. CK was constantly negative in all cases of paraganglioma and constantly positive in all cases of NC. Antibody anti-CK is the single most useful immunomarker for differential diagnosis between paraganglioma, frequently benign neoplasms and NC commonly aggressive in the head and neck. These findings are consistent with the current concepts of the neuroendocrine system.

Hyalinizing trabecular adenoma of the thyroid. A report of three cases with immunohistochemical and ultrastructural studies

We have studied three examples of benign thyroid tumours which conform to the lesion recently described as hyalinizing trabecular adenoma. The prominent feature of this trabecular epithelial lesion is the extracellular deposition of an eosinophilic material that does not show the features of amyloid; the epithelial cells may be elongated, sometimes radially arranged around the eosinophilic material. All three tumours showed positive immunocytochemical staining for thyroglobulin, keratin, chromogranin and neuron-specific enolase. One tumour showed isolated cells with immunoreactivity for somatostatin, argyrophil cytoplasmic granularity with the Grimelius technique, and ultrastructurally demonstrable cytoplasmic electron-dense endocrine granules. The hyaline extracellular material in all three tumours showed strong immunoreactivity for both type IV collagen and laminin. Previous radiation may be important in the causation of this tumour, and it shows a frequent association with severe thyroiditis. We conclude that the main histological feature of this lesion, the hyaline material, is due to the overproduction of a basement membrane-like material by the neoplastic follicular cells. The presence in one tumour of evidence of endocrine differentiation may reflect the potential for follicular cells to show biphasic differentiation, a feature which may be more frequent than has been previously recognized. Several of the other features of this tumour--for example the frequent intranuclear cytoplasmic inclusions--may lead to diagnostic problems, and the entity deserves wider recognition.

Paragangliomas: assessment of prognosis by histologic, immunohistochemical, and ultrastructural techniques

To predict clinical outcome, we studied 42 paragangliomas from 37 patients by routine histology, immunohistochemistry, and electron microscopy. A panel of antisera to neuron-specific enolase (NSE), chromogranin, and met-enkephalin was used to identify chief (type I) cells, and S-100 protein and glial fibrillary acid protein (GFAP) sustentacular (type II) cells. The intensity of staining of type I cells and the density of type II cells were assessed semiquantitatively (0 to 4+) in a total of 38 tumors. A total of 23 of 24 low-grade tumors (solitary, multiple, or associated with other neoplasms; 95.8%) contained type II cells immunoreactive with either S-100 protein or GFAP, and all were positive when S-100 protein and GFAP were used in combination. Five of the nine intermediate-grade (recurrent and/or locally aggressive) tumors were identified as glomus jugulare tumors (GJT). Three intermediate-grade GJTs were devoid of GFAP-reactive type II cells and four GJTs were negative for S-100 protein. Type II cells were identified in only one of five high-grade (malignant) paragangliomas and that tumor contained vanishingly rare cells that were weakly S-100 protein positive but GFAP negative. Sustentacular cell density and chief cell staining intensity were both inversely related to tumor grade. The most sensitive chief cell marker was NSE (92.1%), followed by chromogranin (84.2%). The least sensitive (73.0%) and specific marker was met-enkephalin. Combinations of NSE or chromogranin with met-enkephalin identified chief cells in all cases. Electron microscopy identified neurosecretory granule-containing chief cells, but was of less value in delineating sustentacular cells because of their scarcity and the absence of specific features. By comparison, immunohistochemistry was superior in identifying sustentacular cells. The use of an immunohistochemical panel, in addition to routine histology, can confirm the diagnosis of a paraganglioma and can give an indication of the likely prognosis for a patient.

Histopathology, cytology and cytochemistry of pheochromocytomas and paragangliomas including chemodectomas

The results of histopathological, histochemical and ultrastructural investigations on pheochromocytomas and paragangliomas have been reported. These results allowed the functional identification of the cell types composing many of such tumours. Moreover, comparison of these data with clinico-pathologic findings outlined the advantages and limits of cytologic studies for understanding the natural history of pheochromocytomas and paragangliomas and improving our diagnostic and prognostic criteria.

Multiple endocrine cell types in thyroid medullary carcinoma. Evidence for calcitonin, somatostatin, ACTH, 5HT and small granule cells

10 cases of thyroid medullary carcinoma (TMC) have been studied ultrastructurally and histochemically. Well differentiated calcitonin-producing C cells were present in all tumours, being prevalent in 9 cases. 5-Hydroxytryptamine (5HT) storing cells were found in two cases, somatostatin immunoreactive cells in at least 5 cases and ACTH-immunoreactive cells in 4 cases. Ultrastructurally, at least 3 types of apparently non-C cells were observed. Type 1 cells with large, poorly osmiophilic granules resembling those of gastroenteropancreatic D cells, were present in 6 cases; they appeared to correlate well with somatostatin immunoreactive cells. Type 2 cells with large osmiophilic granules were found in 5 cases; they resembled ACTH-MSH cells of the human pituitary and may correspond to the ACTH-immunoreactive cells of light microscopy. Type 3 cells with small granules and an unknown function were found in 6 cases, always in scarce number. It is concluded that TMC, although mainly made up of C cells, usually contains large proportions of other endocrine cell types.

Nonchromaffin paraganglioma (chemodectoma) of thyroid region

A case of a paraganglioma located over the thyroid cartilage in the midline is reported. The tumor had all the appearances of a carotid body tumor, but its odd location could not be explained on the basis of previously known areas where paraganglionic tissues have been found. Since a paraganglioma has also hitherto been described within the thyroid gland, clinicians and pathologists alike are cautioned that unusually located paragangliomas may be expected in the future.