Insular thyroid carcinoma in adolescents: a potentially lethal endocrine malignancy

Poorly differentiated thyroid carcinoma of childhood and adolescence: a distinct entity characterized by DICER1 mutations

Poorly differentiated thyroid carcinomas (PDTC) in young individuals are rare and their clinical and histopathologic features, genetic mechanisms, and outcomes remain largely unknown. Here, we report a detailed characterization of a series of six PDTC in patients ≤21 years old defined by Turin diagnostic criteria studied for mutations and gene fusions characteristic of thyroid cancer using targeted next-generation sequencing (NGS) and whole-exome sequencing (WES). All tumors had solid, insular, or trabecular growth pattern and high mitotic rate, and five out of six tumors showed tumor necrosis. Targeted NGS assay identified somatic mutations in the DICER1 gene in five of six (83%) tumors, all of which were "hotspot" mutations encoding the metal-ion binding sites of the RNase IIIb domain of DICER1. WES was performed in five cases which confirmed all hotspot mutations and detected two tumors with additional inactivating DICER1 alterations. Of these two, one was a germline pathogenic DICER1 variant and the other had loss of heterozygosity for DICER1. No other mutations or gene fusions characteristic of adult well-differentiated thyroid cancer and PDTC (BRAF, RAS, TERT, RET/PTC, and other) were detected. On follow-up, available for five patients, three patients died of disease 8-24 months after diagnosis, whereas two were alive with no disease. The results of our study demonstrate that childhood- and adolescent-onset PDTC are genetically distinct from adult-onset PDTC in that they are strongly associated with DICER1 mutations and may herald DICER1 syndrome in a minority. As such, all young persons with PDTC may benefit from genetic counseling. Furthermore, their clinically aggressive behavior contrasts sharply with the indolent nature of the great majority of thyroid tumors with DICER1 mutations reported to date.

A rare case of poorly differentiated thyroid carcinoma probably arising from a nodular goiter

Background

Some poorly differentiated thyroid carcinomas (PDTC) arise from pre-existing, well-differentiated carcinomas of follicular cell origin; however, others most likely arise de novo. The case of a PDTC adjacent to a pre-existing nodular goiter is very rare.

Case presentation

A patient had a PDTC, a widely invasive, cellular tumor with cells that lacked the nuclear features of a papillary thyroid carcinoma. Carcinoma cells were arranged in trabecular, solid, and microfollicular histological patterns and displayed high mitotic activity. A nodule partially encapsulated in a thick fibrous capsule was found adjacent to the PDTC. The nodule was composed of small or dilated follicles, without papillary carcinoma-like nuclear features, that were consistent with a nodular goiter. The PDTC showed a high Ki-67 labeling index and an NRAS gene mutation (codon 61, Q61K).

Conclusion

These results support our diagnosis of a PDTC, probably arising from a nodular goiter.

Unusual thyroid tumors: a review of pathologic and molecular diagnosis

The most common thyroid neoplasms are either follicular derived (papillary, follicular and Hürthle cell lesions) or C-cell derived (medullary carcinoma). The diagnosis of these tumors can usually be made at the histologic level, with immunohistochemical stains necessary in some circumstances. Specific molecular mutations have been described that can be diagnostically useful or explain, in part, their pathogenesis, including the well-known Ret/PTC and PPARgamma-PAX8 translocations, point mutations in the Ret, Ras and BRAF genes, and loss of heterozygosity of multiple different tumor suppressor genes. Some unusual tumors of the thyroid gland are more difficult to diagnose. In examining these lesions, the pathologist may use the hematoxylin and eosin-stained morphology, coupled with an analysis of the immunohistochemical staining profiles and possibly analysis of the underlying molecular mutational patterns. These less common thyroid tumors include tall cell and cribriform-morular variants of papillary carcinoma, hyalinizing trabecular tumor, mucoepidermoid and sclerosing mucoepidermoid carcinoma with eosinophilia, poorly differentiated (insular) carcinoma, and undifferentiated (anaplastic) carcinoma. The diagnostic features of these rare tumors, including the histology, immunohistochemical expression profiles and the known molecular mutational profiles of each, are reviewed.

Is there a role for PET-CT and SPECT-CT in pediatric oncology?

During the last decade, hybrid imaging has revolutionized nuclear medicine. Multimodal camera systems, integrating positron emission tomography (PET) or single photon emission computed tomography (SPECT) with computed tomography (CT) now combine the contrast provided by tumor-avid radioactive drugs with the anatomic precision of CT. While PET-CT to a great extent has replaced single-modality PET in adult oncology, the use of PET-CT in children has been controversial, since even the lowest dose CT protocols adds approximately 2 mSv to the radiation dose of about 4 mSv from the PET-study with F-18-fluorodeoxyglucose (F-18-FDG). The article describes the current techniques used, discusses radiation doses and gives an overview of current indications for PET-CT and SPECT-CT in children. Hybrid imaging with a tumor-avid radioactive drug provides extremely high contrast between tumor and background tissues, while the CT component helps to locate the lesion anatomically. Currently both PET-CT and SPECT-CT play a role in pediatric oncology; PET-CT using F-18-FDG particularly for staging and follow-up of lymphoma and brain cancer, bone and soft tissue sarcomas; SPECT-CT with I-123-metaiodobenzylguanidine (MIBG) for tumors of the sympathetic nervous system such as neuroblastoma and pheochromocytoma while the remaining neuroendocrine tumors are imaged with radioactively labeled somatostatin analogues. To reduce radiation dose, a low-dose CT in combination with ultrasound and/or magnetic resonance imaging for the assessment of anatomy is often preferred.

Thyroid carcinoma in children and adolescents-systematic review of the literature

Thyroid cancer in children and adolescents is usually a major concern for physicians, patients, and parents. Controversies regarding the aggressiveness of the clinical presentation and the ideal therapeutic approach remain among the scientific community. The current recommendations and staging systems are based on data generated by studies in adults, and this might lead to overtreating in some cases as well as undertreating in others. Understanding the differences in the biology, clinical course, and outcomes in this population is crucial for therapeutic decisions. This paper evaluates the biology, clinical presentation, recurrences, and overall survival as well as the staging systems in children and adolescents with differentiated thyroid cancer.

Radioiodine treatment in pediatric Graves' disease and thyroid carcinoma

Graves' disease (GD) is the most common cause of hyperthyroidism in pediatric patients. Most pediatric thyroid cancer is differentiated thyroid cancer (DTC). The two diseases can be treated using different methods, such as antithyroid drug, radioactive iodine (RAI), and surgery for GD and surgery and RAI for DTC. RAI can be used to treat pediatric GD and DTC. In the article, we reviewed the RAI application in pediatric GD and DTC.

Poorly differentiated thyroid carcinoma: a cytologic-histologic review

The term poorly differentiated thyroid carcinoma (PDTC) was first proposed in the 1980s, but it was not definitively recognized as a distinct pathologic entity until the most recent classification of endocrine tumors by the World Health Organization in 2004. More recently, as a result of discussions in Turin, Italy, in 2006, diagnostic criteria were made more specific by a consensus of expert thyroid pathologists. The histologic and cytologic aspects are detailed with particular attention to key features helpful in the diagnosis of PDTC, both in surgical pathology and in cytology-based studies. Histologically, insular, solid, and/or trabecular architecture, along with at least one of the following: convoluted nuclei, mitotic activity (>3/10 HPF), or tumor necrosis, are required for a diagnosis of PDTC. Cytologically, the combination of insular, solid, or trabecular cytoarchitectural pattern, single cells, high nuclear to cytoplasmic (N/C) ratio, and severe crowding are highly suggestive of PDTC. Most PDTCs are immunohistochemically positive for thyroglobulin and thyroid transcription factor 1 (TTF-1), and a subset is also positive for p53. On the molecular level, ras mutations are the most common finding. PDTCs are managed aggressively by total thyroidectomy, I, and in some cases, external beam radiotherapy.

Expression of iodine metabolism genes in human thyroid tissues: evidence for age and BRAFV600E mutation dependency

CONTEXT

Children present a higher susceptibility to developing thyroid cancer after radioiodine exposure and also a higher frequency of functional metastases than adults.

OBJECTIVE

To assess the mRNA expression of the sodium/iodide (Na(+)/I(-)) symporter (NIS), the Pendred syndrome gene (PDS), thyroperoxidase (TPO), thyroglobulin (Tg) and TSH receptor (TSH-R) in normal thyroid tissues (NTTs) and papillary thyroid carcinomas (PTCs) among different age groups.

METHODS

Analysis included 59 samples: 21 NTTs and 38 PTCs, of which 21 were the classic type (CPTC) and 17 the follicular variant (FVPTC). Patients were divided into three age groups: I (n = 16) 5-21 years, II (n = 13) 22-59 years, and III (n = 10) 60-91 years. The relative mRNA expression of the five target genes was determinate by quantitative reverse transcription polymerase chain reaction (QRT-PCR).

RESULTS

Expression of all genes was significantly higher in NTTs than in PTCs, and it was not age dependent in the NTT group. Among PTCs, the mean expression of PDS, TPO and TSH-R was significantly lower in group II than in group I. PDS, TPO and Tg expression was significantly lower in classic PTCs than in FVPTCs. The difference was related to a higher frequency of the BRAF(V600E) mutation in the former group.

CONCLUSIONS

The finding of higher PDS, TPO and TSH-R mRNA expression in paediatric vs. adult primary tumour tissues supports the hypothesis that this might contribute to the increased functional activity of metastases in the paediatric group. The finding that mRNA expression of the target genes in NTT was not age dependent does not provide an explanation for the higher susceptibility in the paediatric group.

Childhood thyroid cancer in Belarus, Russia, and Ukraine after Chernobyl and at present

Thyroid cancer in children is usually rare, but in the individuals exposed to radiation risk of disease increases considerably. After the Chernobyl accident in 1986, an over 10-fold maximal elevation in the incidence of thyroid cancer was registered about a decade later, cumulatively resulting in more than a thousand of newly diagnosed cases in children who lived in the territories of Belarus, Russia, and Ukraine affected by radioactive fallouts. Experience from the epidemic substantially promoted knowledge in clinical pediatric oncology, pathology and basic sciences. This article overviews epidemiology, clinical features, results of treatment and follow-up of childhood patients with radiation-induced Chernobyl thyroid cancer in comparison to sporadic cases diagnosed at present. In addition, we discuss general issues of pathology and molecular findings in childhood thyroid carcinomas.

Insular carcinomas of the thyroid exhibit poor prognosis and long-term survival in comparison to follicular and papillary T4 carcinomas

BACKGROUND

Insular thyroid carcinoma was described as a tumor with aggressive behavior, and patients usually present themselves with an advanced tumor stage. Whether the insular component is an independent factor for poor prognosis remains unclear. Therefore, in the present study, we compared the survival of patients with advanced insular, follicular, and papillary thyroid cancer.

MATERIALS AND METHODS

The clinical behavior of tumors in three groups of patients with T4 thyroid carcinoma--8 patients with insular, 11 patients with follicular, and 21 patients with papillary thyroid carcinomas--was compared. Disease-free survival and disease-specific death were analyzed statistically. Cox regression analysis was used to evaluate the influence of histotype and other prognostic factors.

RESULTS

At 3 years, survival was 37.5% (mean 26 months) among patients with insular thyroid carcinoma, 80% (mean 59 months) among those with follicular, and 89% (mean 126 months) among those with papillary thyroid carcinomas (p = 0.007). Disease-free survival in patients without initial distant metastasis was worst in patients with insular thyroid carcinoma (20%) compared to those with follicular (75%) and those with papillary thyroid carcinomas (71%).

CONCLUSION

Patients with advanced insular thyroid carcinoma have a poorer outcome in comparison to patients with similar advanced stage who have follicular or papillary thyroid carcinoma.

Thyroid carcinomas with a variable insular component

BACKGROUND

An insular growth pattern may be observed focally both in papillary and follicular thyroid carcinoma. The aim of the current study was to determine whether a greater extension of the insular component (IC) influences different clinical and histologic features at diagnosis, and a different tumor aggressiveness in terms of frequency in the occurrence of metastases as well as survival.

METHODS

Thirty-three patients with histopathologic findings consistent with IC were included in the study. IC was focal (<50% of the tumor area) in 16 patients and predominant (>50% of the tumor area) in 17 patients. These 2 groups were compared with a control group of 66 patients with differentiated thyroid carcinoma.

RESULTS

At diagnosis, carcinomas with predominant IC differed from those with focal IC with regard to greater tumor size and a higher frequency of extrathyroidal extension and distant metastases. Patient follow-up ranged from 5 to 188 months. The cumulative rate of distant metastases was significantly higher in patients with predominant IC. At the time of last follow-up, carcinomas with predominant IC demonstrated a lesser frequency of disease-free outcome (P = .002) and a higher number of tumor-related deaths (P = .002), either when distant metastases were present (P = .03) or absent (P = .05) at the time of diagnosis.

CONCLUSIONS

The presence of predominant IC is associated with a poor prognosis in terms of ongoing disease or death. Predominant IC should be considered a separate entity from not only the classical papillary or follicular carcinomas but also the focal IC tumor.

[Insular carcinoma of the thyroid. An uncommon but aggressive neoplasm]

Insular carcinoma of the thyroid is an infrequent entity, named in 1984 by Carcangiu when he described its characteristic histology. Clinically and morphologically it is considered to be in an intermediate position between well-differentiated carcinoma of the thyroid (papillary or follicular) and undifferentiated or anaplastic carcinoma of the thyroid. However, most authors believe it to be an independent entity. The prognosis of this tumor is worse than that of classic carcinoma of the thyroid, and most authors advise aggressive therapy, which in some cases can achieved prolonged survival. We describe 2 patients who experienced recurrence after treatment for the primary tumor. The recurrences were treated but the clinical courses differed.

Prognostic Factors of Insular versus Papillary/Follicular Thyroid Carcinoma

The study aims were to characterize patients with insular thyroid cancer and to provide data on patient outcome after surgical therapy. We compared nine patients with insular thyroid cancer at the Department of Surgical Science of “La Sapienza” University of Rome with 27 patients of similar age and tumor size who had follicular and papillary cancer, for a minimum follow-up period of 24 months (range, 24–72 months). All of the patients examined underwent total thyroidectomy. Vascular invasion was observed in 44.4 per cent of insular carcinomas ( P < 0.05 vs papillary carcinomas). No significant differences were observed regarding diagnostic method, multifocality, tumor nodes metastases (TNM), or stage. The death rate of patients with insular carcinoma (33.3%) was found to be higher than that of patients with follicular carcinoma ( P < 0.05) and papillary carcinoma ( P < 0.01). Relapsing lymph-node pathologies were observed in 4 patients (44.4%) with insular carcinoma ( P < 0.05 vs those with follicular and papillary carcinomas). Distant metastases were observed in 66.6 per cent of insular carcinomas ( P < 0.005 vs follicular carcinoma and P < 0.001 vs papillary carcinoma). At the end of follow-up, 2 patients (22.2%) with insular carcinoma were disease-free ( P < 0.001 vs those with follicular and papillary carcinomas). Our study demonstrates an unfavorable prognostic role of the insular phenotype of thyroid cancer, such that this tumor can be classified as an autonomous clinical and pathological entity.

Insular carcinoma of the thyroid with jugular vein invasion

BACKGROUND

Gross angioinvasion with intraluminal tumor thrombus is rarely seen in thyroid cancer, with few cases reported in the literature.

METHODS

We report an insular carcinoma of the thyroid displaying this aggressive local invasion and angioinvasion of the internal jugular chain. Complete surgical removal of the intraluminal disease, regional metastasis, and primary tumor was carried out.

RESULTS

Adjuvant external beam radiation therapy and iodine-131 were administered, and the patient died with pulmonary metastases 30 months after surgery. No locoregional recurrence was noted at last follow-up.

CONCLUSIONS

Treatment of insular carcinoma of the thyroid with invasion of the internal jugular vein is amenable to surgical resection. Postoperative radioactive iodine and external beam radiotherapy can achieve locoregional disease control and prolonged survival.

Insular carcinoma of the thyroid in an adolescent: a case report and review of the literature

A 15-year-old girl was referred for a thyroid gland mass, which rapidly enlarged in the brief interval between initial evaluation and surgery. Fine needle aspiration of the mass suggested a diagnosis of papillary thyroid carcinoma. Upon pathological examination of this aggressive tumor, an "insular" pattern of tumor was identified. Insular carcinoma of the thyroid gland is unusual in the pediatric age group, however its aggressive nature and prognosis have important management implications for those physicians involved in the care of affected patients. Aggressive surgical debulking, very close observation of the course of disease, and adjunctive radioiodine therapy may all be indicated as were performed in this case. A description of the pathology of this condition, and a review of the clinical experience with insular carcinoma in childhood and adolescence are presented.

RET and NTRK1 proto-oncogenes in human diseases

RET and NTRK1 are receptor tyrosine kinase (RTK) proteins which play a role in the development and maturation of specific component of the nervous system. Their alterations have been associated to several human diseases, including some forms of cancer and developmental abnormalities. These features have contributed to the concept that one gene can be responsible for more than one disease. Moreover, both genes encoding for the two RTKs show genetic alterations that belong to either "gain of function" or "loss of function" class of mutations. In fact, receptor rearrangements or point mutations convert RET and NTRK1 in dominantly acting transforming genes leading to thyroid tumors, whereas inactivating mutations, associated with Hirschsprung's disease (HSCR) and congenital insensitivity to pain with anhidrosis (CIPA), impair RET and NTRK1 functions, respectively. In this review we have summarized the main features of the two receptors, their physiological and pathological roles. In addition, we attempted to identify the correlations between the different genetic alterations and the related pathogenetic mechanisms.

Insular Carcinoma of the Thyroid

Thyroid surgeons are becoming increasingly more aware of a histologically distinct subset of thyroid carcinoma whose classification falls between well-differentiated and anaplastic carcinomas with respect to both cell differentiation and clinical behavior. This subtype of tumors has been categorized as poorly differentiated or insular carcinoma, based on its characteristic cell groupings. Although the differentiation of insular carcinoma from other thyroid carcinomas has important prognostic and therapeutic significance, relatively little about insular carcinoma has been published in the otolaryngology literature. In this article, we describe a new case of insular carcinoma and we discuss the findings of our review of the literature. We conclude that insular thyroid carcinoma warrants aggressive management with total thyroidectomy followed by radioactive iodine ablation of any remaining thyroid tissue.

Long-term outcome of patients with insular carcinoma of the thyroid: the insular histotype is an independent predictor of poor prognosis

BACKGROUND

Insular thyroid carcinoma was described originally as a tumor with aggressive behavior. However, whether a predominant insular component is an independent factor for poor prognosis is unclear.

METHODS

The authors compared the clinical behavior of tumors in three groups of patients with thyroid carcinoma--13 patients with insular thyroid carcinoma, 18 patients with follicular thyroid carcinoma, and 26 patients with papillary thyroid carcinoma--who were selected based on similar tumor size and similar age. Disease free survival and disease specific deaths were assessed in the three groups with a Kaplan-Meier analysis and were compared using the log-rank test. Cox regression analysis was used to evaluate the influence of histotype and other prognostic factors on the occurrence of distant metastases and disease specific death.

RESULTS

Patient follow-up ranged from 5.2 months to 190.0 months. At last follow-up, only 1 of 13 patients (7.7%) with insular carcinoma, compared with 8 of 18 patients (44.4%) with follicular carcinoma and 12 of 26 patients (46.1%) with papillary carcinoma, were disease free. The disease specific death rate was 61.5% among patients in the insular carcinoma group compared with 16.7% and 15.4% among patients in the follicular carcinoma group (P = 0.006) and the papillary carcinoma group (P = 0.025), respectively. At multivariate analysis, the insular histotype was the only variable that was related independently to disease specific death (hazard ratio = 4.27; P = 0.005). Distant metastases occurred in 84.6% of patients in the insular carcinoma group compared with 50% and 19.2% of patients in the follicular carcinoma group (P = 0.039) and the papillary carcinoma group (P = 0.0003), respectively. All metastases from patients with insular carcinomas (n = 11 patients) showed radioiodine uptake, but a clinical benefit from this treatment was observed only in 1 patient.

CONCLUSIONS

Patients with insular thyroid carcinoma have a poorer outcome compared with patients of similar age who have differentiated types of thyroid carcinoma with tumors of a similar size. Because radioiodine rarely is effective in the treatment of patients with metastatic insular thyroid carcinoma, novel and possible multimodal therapies should be explored for the treatment of patients with these aggressive tumors.

Cytopathology of insular carcinoma of the thyroid

Four pure insular carcinomas (IC) and one IC with focal anaplastic carcinoma (AC) of the thyroid with cytologic evaluation by fine-needle aspiration (FNA) were reviewed. The needle aspirates from the four pure ICs revealed abundant monomorphic follicular cells present singly, in small, loose aggregates, and in cohesive trabecular and acinar clusters. Tumor cells showed fragile, ill-defined, granular cytoplasm and oval nuclei with conspicuous or inconspicuous nucleoli. The case of IC with focal AC yielded, in addition to the follicular cells as seen in the FNA of the 4 cases of pure IC, large pleomorphic malignant cells with prominent nucleoli that were characteristic for an AC, giant-cell type. No intact insulae of tumor cells were identified in any of the 5 cases. Thus, a thyroid IC may be suspected if abundant cohesive and dyshesive monomorphic follicular cells are present in the tumor FNA. However, a firm diagnosis of thyroid IC can only be made by histologic examination of the excised tumor.

FDG positron emission tomographic, radioiodine, and MIBI imaging in a patient with poorly differentiated insular thyroid carcinoma

Poorly differentiated insular thyroid carcinoma is now classified as a separate entity among other tumors of the thyroid gland. Its histologic pattern and its clinical course are regarded as intermediate between well differentiated and anaplastic thyroid cancer. Insular carcinoma accumulates I-131, but no data exist regarding its fluorodeoxyglucose (FDG) positron emission tomographic (PET) uptake. The authors report F-18 FDG PET, Tc-99m MIBI, and radioiodine imaging features in a 63-year-old patient with metastatic insular thyroid carcinoma. After total thyroidectomy (for poorly differentiated insular carcinoma pT3a), the patient was referred for radioiodine ablation. No signs of recurrence were present until 16 months later, when thyroglobulin levels increased. An I-131 scan showed a single lesion in the right lung, and further radioiodine treatment was administered (cumulative dose [530 mCi], 19,610 MBq I-131). Three years after the initial diagnosis, FDG-PET and Tc-99m MIBI scans were performed within 5 days during thyroxine treatment. After that, thyroxine substitution was withdrawn; 6 weeks later, an I-131 whole-body scan was performed. Both radioiodine and MIBI images showed increased tracer uptake in the known lung lesion. However, FDG PET showed a normal tracer distribution. Magnetic resonance and computed tomographic imaging confirmed a 12-mm lesion in the right upper lobe. These findings support the concept of the "flip-flop phenomenon" in insular thyroid carcinoma, an alternating pattern of metastases with either I-131 or FDG-uptake. Despite poorly differentiated histologic findings, glucose metabolism was not increased in this patient with an insular tumor.

Advanced insular thyroid carcinoma in a fourteen-year-old girl: twenty-four years of follow-up

Insular thyroid carcinoma has become a separate entity among thyroid malignancies. It is regarded as intermediate in aggressiveness between well-differentiated and anaplastic thyroid carcinomas. Reports on the clinical course of children with insular thyroid carcinoma are rare. We report the case of a 14-year-old girl who was admitted to our thyroid outpatient ward in 1975 with a scintigraphic cold thyroid nodule and multiple enlarged cervical lymph nodes. Chest radiography showed metastases in both lungs. After total thyroidectomy and, central and modified unilateral radical neck dissection, the girl was given a dose of 80 mCi 131I. Posttherapeutic scan demonstrated diffuse tracer uptake in both lungs. A second dose of 200 mCi 131I was administered 4 months later and another dose of 150 mCi 131I in July 1976. Subsequently, whole-body scans showed inconspicuous tracer distribution and chest x-rays were normal. The patient was treated with levothyroxine and followed until 1982, when she left Vienna. In 1999, the patient was contacted for reexamination. She has been well and had had two healthy children. The patient was taking 150 microg levothyroxine daily; she had a normal TSH value and her thyroglubulin was 0.3 ng/mL. Chest radiography and sonography of the neck showed no pathological findings. The paraffin sections of the patient's tumor were reexamined in 1999 and demonstrated the histologic characteristics of a poorly differentiated insular thyroid carcinoma (pT4a, pN1a, M1). These findings demonstrate that even in advanced stages, insular thyroid carcinoma treatment can be successful.

Anaplastic thyroid carcinoma: a therapeutic challenge

Anaplastic thyroid carcinoma is an extremely aggressive solid tumor that resists most therapeutic efforts and is almost always fatal. It typically arises as a terminal dedifferentiation of unrecognized long-standing differentiated thyroid carcinoma. Current chemotherapeutic agents are not capable of consistent beneficial therapeutic responses, although rare patients may gain additional months of survival. Aggressive local tumor control with surgery and external beam radiotherapy may provide palliation and delay eventual death from distant metastatic disease. This disease challenges clinicians and researchers to develop new systemic therapies as well as to aggressively treat differentiated thyroid cancers before they become anaplastic tumors.

Anaplastic thyroid carcinoma: behavior, biology, and therapeutic approaches

Anaplastic thyroid carcinoma (ATC), although exceedingly rare, is the most aggressive solid tumor known. Early studies on the effects of different therapies may be biased by the inclusion of responsive "small cell" ATC patients, which are now known to be mostly lymphoma patients. Local control of disease with surgery and/or external beam radiotherapy (XRT) is of fundamental importance to enhance survival. Ultimately, nearly all ATC patients die from their disease, which is widely metastatic. Development of effective systemic chemotherapy agents would provide the best chance for long-term survival of patients. Early preliminary data suggest that paclitaxel may be helpful, although no agent has yet been identified to result in dramatic improvements in survival. Select patients may benefit from aggressive multimodal therapy, although it is important to provide appropriate palliative care when desired.

Macrofollicular variant of papillary thyroid carcinoma with minor insular component

BACKGROUND

The macrofollicular variant of papillary thyroid carcinoma that is the subject of this study has only recently been characterized. Information about its morphologic spectrum and biologic behavior is limited.

METHODS

The authors reviewed 29 examples, including 17 previously reported cases. The clinical and pathologic features of five patients who had the macrofollicular variant of papillary thyroid carcinoma with a minor insular component were analyzed in detail. The insular component in thyroid carcinomas has been associated with aggressive clinical behavior.

RESULTS

The ages of the 5 patients ranged from 31 to 70 years; the mean age was 40 years. Three patients presented with a palpable thyroid nodule and two with a large thyroid mass of long duration. The latter two tumors, which metastasized, were the largest (8 and 11 cm) and showed extrathyroidal and blood vessel invasion. All five tumors were composed predominantly of macrofollicles (>50%) and had a minor insular component that comprised less than 5% of the tumor mass. In most tumors, the macrofollicles were lined by cells with large, clear, grooved nuclei, and all five contained areas of conventional follicular variant of papillary thyroid carcinoma. In the two that metastasized, however, the lining of many macrofollicles consisted of cuboidal cells with small, hyperchromatic, follicular-type nuclei. Only the macrofollicular component was identified in the metastatic deposits in these two patients. All five patients were alive at last follow-up, two with metastases; but follow-up for this study is limited.

CONCLUSIONS

A minor insular component is an additional feature of the macrofollicular variant of papillary thyroid carcinoma that may aid in diagnosis and does not appear to have an adverse effect on the excellent prognosis of patients with these tumors.