Undifferentiated thyroid tumors of diffuse small cell type. Histological and immunohistochemical evidence for their lymphomatous nature

Anaplastic thyroid carcinoma: from clinicopathology to genetics and advanced therapies

Anaplastic thyroid carcinoma (ATC) is a rare malignancy, accounting for 1-2% of all thyroid cancers. Although rare, ATC accounts for the majority of deaths from thyroid carcinoma. ATC often originates in a pre-existing thyroid cancer lesion, as suggested by the simultaneous presence of areas of differentiated or poorly differentiated thyroid carcinoma. ATC is characterized by the accumulation of several oncogenic alterations, and studies have shown that an increased number of oncogenic alterations equates to an increased level of dedifferentiation and aggressiveness. The clinical management of ATC requires a multidisciplinary approach; according to recent American Thyroid Association guidelines, surgery, radiotherapy and/or chemotherapy should be considered. In addition to conventional therapies, novel molecular targeted therapies are the most promising emerging treatment modalities. These drugs are often multiple receptor tyrosine kinase inhibitors, several of which have been tested in clinical trials with encouraging results so far. Accordingly, clinical trials are ongoing to evaluate the safety, efficacy and effectiveness of these new agents. This Review describes the updated clinical and pathological features of ATC and provides insight into the molecular biology of this disease. The most recent literature regarding conventional, newly available and future therapies for ATC is also discussed.

Poorly Differentiated and Anaplastic Thyroid Cancer

BACKGROUND

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic (undifferentiated) thyroid carcinoma (ATC) comprise a small subset of thyroid tumors that are associated with a poor prognosis and account for a significant portion of the morbidity and mortality related to thyroid cancer. Since management strategies vary between these two entities, it is important for clinicians to be able to differentiate PDTC from ATC.

METHODS

We reviewed the literature on PDTC and ATC and compared clinical and histopathologic features important in defining the disease process.

RESULTS

Both PDTC and ATC display aggressive behavior with increased locoregional and distant disease. In most cases, patients are older and have large, locally advanced tumors. PDTC may represent an intermediate entity in the progression of well-differentiated thyroid carcinoma to ATC. The use of surgical management may be curative or palliative and differs between PDTC and ATC. The roles of radiotherapy and chemotherapy have not been well described.

CONCLUSIONS

PDTC and ATC are rare diseases that carry a poor prognosis. Recognition of their different clinicopathologic features is important to the optimal management of these tumors.

Surgical management of thyroid cancer

Thyroid cancer is the most common endocrine neoplasm; however, it only accounts for less than 1% of all human malignances. Thyroid cancers are divided into well differentiated and non-well differentiated cancers, according to their histology and behavior. The surgical management options of well-differentiated thyroid cancer include total or near-total thyroidectomy, subtotal thyroidectomy and lobectomy plus isthmusectomy. The extent of surgery for thyroid cancer continues to be an area of controversy. Complications associated with thyroid surgery are directly proportional to the extent of thyroidectomy and inversely proportional to the experience of the operating surgeon. They occur less frequently with good surgical technique and better understanding of surgical anatomy, and include wound healing and infections (seroma, hematoma and wound infection), nerve injury, hypoparathyroidism, hypothyroidism, postoperative hemorrhage and respiratory obstruction.

American Thyroid Association guidelines for management of patients with anaplastic thyroid cancer

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Rapid evaluation and establishment of treatment goals are imperative for optimum patient management and require a multidisciplinary team approach. Here we present guidelines for the management of ATC. The development of these guidelines was supported by the American Thyroid Association (ATA), which requested the authors, members the ATA Taskforce for ATC, to independently develop guidelines for ATC.

METHODS

Relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The quality and strength of recommendations were adapted from the Clinical Guidelines Committee of the American College of Physicians, which in turn was developed by the Grading of Recommendations Assessment, Development and Evaluation workshop.

RESULTS

The guidelines include the diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, systemic therapy, supportive care during active therapy), approaches to advanced/metastatic disease, palliative care options, surveillance and long-term monitoring, and ethical issues including end of life. The guidelines include 65 recommendations.

CONCLUSIONS

These are the first comprehensive guidelines for ATC and provide recommendations for management of this extremely aggressive malignancy. Patients with stage IVA/IVB resectable disease have the best prognosis, particularly if a multimodal approach (surgery, radiation, systemic therapy) is used, and some stage IVB unresectable patients may respond to aggressive therapy. Patients with stage IVC disease should be considered for a clinical trial or hospice/palliative care, depending upon their preference.

Cytologic features of mixed papillary carcinoma and chronic lymphocytic leukemia/small lymphocytic lymphoma of the thyroid gland

We report a case of papillary thyroid carcinoma (PTC) and chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma of the thyroid gland. To the best of our knowledge, this is the first such case to be reported in the cytology literature. An 81-year-old male with known CLL presented for routine physical examination and was found to have a left-sided thyroid nodule. Thyroid ultrasound showed a calcified nodule. Fine-needle aspiration biopsy (FNAB) was performed and revealed PTC and an atypical lymphoid infiltrate that was suspicious for lymphoma. A partial thyroidectomy was performed and confirmed PTC with concurrent gland involvement by chronic lymphocytic leukemia/small lymphocytic lymphoma (SLL).

Small cell carcinoma of the head and neck: a review

Small cell carcinoma (SCC) has become recognized as a distinct, though relatively infrequent, clinical pathology that occurs in multiple sites throughout the head and neck. Excluding cases that are considered to arise from skin, SCC in the head and neck has been found to develop in nearly all structures associated with the upper aerodigestive tract. Among the head and neck sites, the frequency of SCC is greatest in the larynx, with salivary glands and the sinonasal region comprising the other principle areas of origin. Controversy exist as to whether SCC can develop as a distinct entity in the thyroid, with most tumors that previously would have been considered as SCC now found to be lymphomas or variant forms of other types of thyroid malignancy. While there seems to be some differences among tumors arising from the various subsites, in general all SCC that originate in the head and neck have a tendency for aggressive local invasion and a strong propensity for both regional and distant metastasis. Treatment may include surgical resection, radiotherapy, chemotherapy, or some combination of these modalities. Due to the infrequency of these tumors, it is very unlikely that any large, controlled study will ever be done. For this reason, recommendations for treatment of SCC arising in the head and neck are based primarily on retrospective data from various small case series and on comparative data for treatment of SCC of bronchogenic and other extrapulmonary origin. Although patients with truly limited local disease may enjoy some prolonged survival, most patients with this tumor do poorly despite all current attempts at treatment.

Anaplastic Thyroid Carcinoma: Biology, Pathogenesis, Prognostic Factors, and Treatment Approaches

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors known to affect humans and carries a dismal prognosis. Our primary aim was to review its epidemiology, biology, risk factors, and prognostic indicators. We also reviewed the individual and combined roles of surgery, radiotherapy, chemotherapy, and newer therapeutic options in the management of ATC.

METHODS

An extensive literature review was conducted to include all published reports on ATC. The changing trends in the management of anaplastic thyroid cancer were analyzed to summarize the current practice of management of ATC.

RESULTS

Although ATC is rare, there has been a decline in its incidence worldwide. ATC accounts for more than half of the 1200 deaths per year attributed to thyroid cancer. Long-term survivors are rare, with >75% and 50% of patients harboring cervical nodal disease and metastatic disease, respectively, at presentation. ATC can arise de novo or from preexisting well-differentiated thyroid cancer. Surgical management has shifted from tracheostomy only for palliation to curative resection when possible. Tracheostomy is performed for impending obstruction rather than for prophylaxis. Radiotherapy has evolved from postoperative administration only to preoperative treatment, combining preoperative and postoperative treatment and using higher doses, along with hyperfractionating and accelerating dose schedules. Chemotherapy has changed from monotherapy to combination therapy, and newer drugs such as paclitaxel show promise. Similarly, novel angiogenesis-inhibiting agents are currently being used, with early reports of some benefit.

CONCLUSIONS

Despite multimodality approaches, ATC still carries a dismal prognosis. This should provoke innovative strategies beyond conventional methods to tackle this uniformly lethal disease.

Prognostic factors of anaplastic thyroid carcinoma

BACKGROUND AND PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies. We tried to elucidate the possible prognostic factors.

METHODS

A retrospective review was conducted of ATC patients in National Taiwan University Hospital from 1978 to 2003. Their demographic characteristics, clinical presentations, laboratory data and treatment modalities were reviewed. Possible prognostic factors for survival were evaluated.

RESULTS

Forty-five patients (14 males and 31 females) of mean age 61.9 +/- 12.6 yr were included in this study. The median survival time was 94 days (range 6 to 776 days). The overall survival rate was 27% at 6 months and 10% at 1 yr. Thirty-two patients receiving intervention regimens had a median survival of 106 days, while 13 patients receiving palliative therapy had a median survival of 39 days. The difference in survival is statistically significant (logrank test, p = 0.017). Adjusted with sex and age, increment in white blood cell count (per 10(9)/l) and serum albumin (per 1.0 g/l) had a hazard ratio of 1.12 (Cox regression, p < 0.001) and 0.92 (p = 0.041), respectively. Patients with leukocytosis [white blood cell (WBC) count > 10(10)/l] or hypoalbuminemia (serum albumin < 35 g/l) had significant shorter survival than patients without leukocytosis or hypoalbuminemia (logrank test p = 0.008 and p = 0.032, respectively). Patients with serum T4 levels lower than 64.35 nmol/l had significantly shorter survival than patients without hypothyroxinemia (median survival 24 vs 128 days, logrank test, p = 0.004).

CONCLUSIONS

ATC is an aggressive malignancy. Leukocytosis, hypoalbuminemia and hypothyroxinemia indicated poor prognosis. Survival time might be prolonged if intervention treatment is tolerable.

Anaplastic thyroid cancer

Anaplastic thyroid carcinoma is one of the most aggressive malignancies, with a poor prognosis. Although rare, representing only 2% of clinically recognized thyroid cancers, the overall median survival is limited to months. Most patients are elderly and seek treatment with a rapidly growing mass. Almost half the patients seek treatment with distant metastases, with as many as 75% developing distant disease during their illness. In most the patients, complete surgical resection is not possible. There are, however, a few patients with resectable disease reported in the literature who have demonstrated long-term survival with aggressive multimodal therapy that included surgery, radiation, and chemotherapy. Preclinical studies in human anaplastic thyroid carcinoma cell lines show promise that new approaches to the management of this disease will be found in the future. Until such time when an effective regimen is found, all patients with anaplastic thyroid carcinoma should be evaluated for multimodal therapy in the setting of a clinical trial.

The pathology of autoimmune thyroid disease: a review

Lymphocytic infiltration of the thyroid gland is the pathologic hallmark of autoimmune thyroid disease. Lymphoid cells are seen in the stroma of glands affected by Graves' disease. However, large lymphoid infiltrates are characteristic of that spectrum of diseases conveniently termed chronic lymphocytic thyroiditis. In this review, the pathology of the various subtypes of chronic thyroiditis is enumerated, including recently defined lesions, i.e., painless thyroiditis, thyroiditis associated with interleukin chemotherapy, and peritumor thyroiditis are reviewed. The unifying morphologic characteristics seen in these conditions are discussed.

Immunohistochemical analysis of small cell tumors of the thyroid gland: an Eastern Cooperative Oncology Group study

The majority of small cell anaplastic tumors of the thyroid gland are generally believed to be non-Hodgkin's lymphomas, including most of those formerly classified as small cell carcinomas. Using a panel of antibodies capable of detecting epithelial, neuroendocrine, and B and T cells in paraffin-embedded tissue sections, we studied 68 thyroid neoplasms in which the original diagnosis was small cell carcinoma or lymphoma. Sixty-three of the tumors were identified as lymphomas of B-cell origin on the basis of L26 reactivity used in conjunction with light chain restriction and MB2 immunostaining. Two additional tumors were classified as lymphomas of indeterminate phenotype. Immunophenotyping indicated an epithelial origin in the remaining three tumors. No cases of medullary carcinoma were detected by immunostaining. Histologic review revealed a predominance of large cell and immunoblastic lymphomas, with low-grade lymphomas of mucosa-associated lymphoid tissue histology accounting for only five cases. Our findings indicate that the majority of small cell anaplastic tumors of the thyroid are B-cell lymphomas. Although primary small cell carcinoma of the thyroid may rarely occur, this diagnosis should not be made without immunohistologic confirmation.

Thyroid cancer

There have been important recent advances in our understanding of the biologic nature of thyroid cancer and in the early diagnosis of the disease. Despite these advances, there is still considerable controversy over the management of thyroid cancer, including the extent of surgery, the indications for the use of iodine-131, the effectiveness of thyroid-stimulating hormone suppression, and the prediction of outcome. In this review, the current status of the diagnosis and management of the various types of thyroid cancer are carefully reviewed and extensively documented.

Calcitonin free oat-cell carcinoma of the thyroid gland

Two cases of primary oat-cell carcinoma of thyroid, in a 63-year-old woman and a 73-year-old man, are described. Case 1 was a compound tumour with the oat-cell component merging with a papillary component. Both tumours, in addition to histological features consistent with oat-cell carcinoma, showed immunohistochemical positivity with anti-chromagranin A and anti-synaptophysin antisera. Negative results were obtained when anti-calcitonin and anti-thyroglobulin antisera were employed. Using in situ hybridization, chromogranin A and B messenger RNAs were localized with biotinylated oligonucleotide probes. In contrast, with in situ hybridization, no localization for calcitonin messenger RNA was seen using radioactive and biotinylated probes. It is concluded that these calcitonin-free, small-cell carcinomas should be considered separately from medullary thyroid carcinomas and be regarded as a distinct entity, probably the thyroid equivalent of oat-cell carcinomas of the lung.

The WHO histological classification of thyroid tumors: a commentary on the second edition

This article introduces the revised WHO classification of thyroid tumors, giving an account of the major changes made and the reasons behind the changes, as well as listing the actual classification now recommended. It is intended to draw general attention to the revision, the full version of which will be published separately.

Anaplastic thyroid carcinoma. A clinical, histologic, and immunohistochemical study

Twenty-six cases of anaplastic thyroid tumor were investigated and reclassified using immunoperoxidase techniques. Sections of the neoplasms were stained immunohistologically for the following thyroid associated antigens: (1) thyroglobulin, which shows a positive reaction with follicular cells of the thyroid; (2) calcitonin, which is positive in medullary carcinoma of the thyroid; and (3) leucocyte common antigen (LC), which identifies lymphomata and Factor VIII-related antigen for hemangioendothelioma. Using these methods, five cases were reclassified. Three cases were identified as lymphomata, one case was reclassified as medullary carcinoma of the thyroid, and one case was identified as hemangioendothelioma. Eleven cases were confirmed to be anaplastic carcinoma of the thyroid and ten cases were negative for all the antigens tested. There was a significant difference in the survival of the groups of patients mentioned above. Prognostic data support the suggestion that immunohistochemical methods should be used for the precise classification of anaplastic carcinoma. In this way, tumors such as malignant lymphoma and medullary carcinoma, which resemble anaplastic carcinoma histologically but have a better prognosis, can be identified. This is important for planning surgical procedures and choosing chemotherapy and/or radiotherapy.

The value of immunocytochemical methods in the differential diagnosis of anaplastic thyroid tumours

The practical usefulness of a panel of monoclonal antibodies recognising epithelial and lymphoid antigens has been evaluated on a series of 10 routinely processed thyroid tumours of uncertain origin. All 6 small cell tumours were shown to be of lymphoid origin whereas of the 4 large cell tumours two were lymphomas and two carcinomas. Two of the tumours, one large cell and one small cell, were undiagnosable due to technical reasons (crush artefact or small size of biopsy) and emphasized the value of immunohistology in this context. Clinical follow-up of all 10 cases indicated that these distinctions are of both prognostic and therapeutic value. It is concluded that immunocytochemistry using a carefully selected panel of monoclonal antibodies is a valuable and convenient means of making an objective distinction between anaplastic thyroid tumours of epithelial or lymphoid origin.