Diagnostic Dilemmas in Thyroid Pathology: Follicular Variant of Papillary Thyroid Carcinoma and Classic Papillary Thyroid Carcinoma Arising in Lymphocytic Thyroiditis:

Metastatic Thyroid Carcinoma to the Kidneys Presenting Initially as Bilateral Renal Masses: A Rare Case Report and Literature Review

Thyroid cancers exist in multiple forms. Papillary and follicular carcinomas of the thyroid are often referred to as well-differentiated thyroid cancers. Well-differentiated thyroid cancers rarely present as a distant metastatic cancer on initial diagnosis. Papillary thyroid cancer tends to have a good prognosis; however, if distant metastasis of PTC is present, there is usually a poor clinical outcome with a less favorable prognosis. In this study, we report a 90-year-old female who presented with right-sided abdominal discomfort. A renal ultrasound revealed bilateral upper pole renal masses. A percutaneous biopsy was ordered, and the microscopic examination revealed bilateral renal metastasis with a follicular variant of papillary thyroid carcinoma. The patient underwent thyroidectomy and sustained radiation therapy for her bilateral renal metastases. She died 6 years after her initial diagnosis, due to sepsis. This is the second study in literature to report bilateral renal metastasis of follicular variant of papillary thyroid cancer.

Current role and value of fine-needle aspiration in nodular goitre

Thyroid nodules are common and, depending on the detection technique used, can affect 50% or greater of the population. The primary diagnostic test to assess the nature of these nodules is fine-needle aspiration cytology. Most thyroid nodules are benign and often are multiple. However, the morphology of these nodules may mimic neoplasms showing features such as papillary growth, micro-follicles and even oncocytic metaplasia. Lesions with these features may be considered indeterminate for neoplasm or malignancy, and often require surgical excision to define their nature. The role of cytopathology in this area is to screen those definitely benign nodules, thus preventing surgery and reassuring both the patient and the clinician. In this review, we demonstrate many of the morphological manifestations of nodular goiter and stress the necessity of careful preparatory techniques. Although the past several years have witnessed the development of molecular testing to refine diagnostic cytology in the thyroid, it is still the role of the cytopathologist to identify those "indeterminant" nodules which should be tested. Thus, the cytopathologist contributes both an essential diagnostic and an important cost saving role which hopefully will continue in the future.

Papillary Thyroid Cancer and Hashimoto's Thyroiditis: An Association Less Understood

Hashimoto's thyroiditis (HT), part of the spectrum of autoimmune thyroid diseases is a major cause of thyroid hypofunction worldwide. Papillary thyroid carcinoma (PTC), the most prevalent of all thyroid carcinomas has been associated with HT. Literature on this association are based on preoperative FNA or post thyroidectomy histopathology reports, which are subject to potential biases. Molecular, hormonal and histopathalogical basis of this association has been hypothesized, however a definite causal association has not been proved till date. This review aims to study the basis of this association and clinical features and management of HT concurrent with PTC. There are no distinctive clinical or radiological features that categorically differentiates HT concurrent with PTC from PTC or which can pick up a nodule harboring PTC in setting of HT. Smaller nodule size and radiological features like hypoechogenecity; hyper vascularity and calcification in a clinical setting of hypothyroidism have a higher odds ratio for malignancy and merit further investigations. PTC associated with HT has been seen to be less aggressive with earlier presentation with lesser chances of extra thyroidal extension and lymph nodal metastasis. The management and follow up of PTC in HT is no different from that of PTC alone. The prognosis of PTC concurrent with HT is better compared to age and stage matched PTC in terms of lower recurrence and disease free and overall survival.

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.

Clinical features of thyroid autoimmunity are associated with thyroiditis on histology and are not predictive of malignancy in 570 patients with indeterminate nodules on cytology who had a thyroidectomy

BACKGROUND

The relationship between thyroid autoimmunity and cancer is still uncertain.

PATIENTS

We approached this issue in 570 consecutive patients submitted to thyroidectomy for an indeterminate nodule on cytology. Thyroid autoimmunity was defined as positivity of circulating thyroid autoantibodies (TAb), autoimmune hypo- or hyperthyroidism, thyroid hypoechogenicity on ultrasound, and lymphocytic infiltration on histology.

RESULTS

TAb were found in 122/570 (21.4%), hypoechogenicity in 115/570 (20.1%), and lymphocytic infiltration in 117/570 (20.5%) of patients. The three features of thyroid autoimmunity were highly concordant: hypoechogenicity was observed in 71/448 (15.8%) patients with negative TAb and in 44/122 (36%) with positive TAb (P < 0.0001); lymphocytic infiltration was found in 53/448 (11.8%) patients with negative TAb and in 64/122 (52.4%) with positive TAb (P < 0.0001); hypoechogenicity on ultrasound was observed in 73/453 (16.1%) patients without, and in 42/117 (35.9%) with lymphocytic infiltration (P < 0.0001). None of these parameters was associated with malignancy. TAb were found in 32/135 (23.7%) patients with carcinoma and in 90/435 (20.6%) with a benign lesion (P = NS); hypoechogenicity was observed in 26/135 (19.2%) patients with carcinoma and in 89/435 (20.4%) patients with benign lesions (P = NS); lymphocytic infiltration was present in 28/135 (20.7%) patients with carcinoma and in 89/435 (20.4%) with benign lesions (P = NS). The frequency of cancer in 11 patients with clinically overt thyroid autoimmune disease did not differ from that observed in the whole study group.

CONCLUSION

In this group of patients with indeterminate thyroid nodules at cytology, clinical and pathological criteria of thyroid autoimmunity were strongly concordant and not associated with malignancy.

Combined clinical, thyroid ultrasound and cytological features help to predict thyroid malignancy in follicular and Hupsilonrthle cell thyroid lesions: results from a series of 505 consecutive patients

OBJECTIVE

The cytological patterns of follicular and Hupsilonrthle cell nodules are included among the indeterminate results of fine-needle aspiration cytology, because distinction between benign and malignant lesion can only be made on histological criteria. The diagnostic value of atypia at cytology, clinical parameters and echographic patterns were examined to establish the risk of malignancy in 505 patients with follicular and Hupsilonrthle cell thyroid nodules at cytology.

DESIGN AND PATIENTS

The study included 505 consecutive patients who had undergone thyroidectomy from the period 2002-2005.

RESULTS

Histological diagnosis of malignancy was carried out in 125 of 505 (25%) patients, the follicular variant of papillary carcinoma being the most frequent histotype. Only atypia at cytology (P < 0.0001) and spot microcalcifications at ultrasound (P = 0.009) were predictive of malignancy. Male gender, normal thyroid volume, single nodularity, nodule hypoechogenicity, size and blurred margins were associated with malignancy, although not significantly. An arbitrary clinical score allowed the identification of patients with high (41%, 110 patients) and low (16%, 242 patients) risk of malignancy. Combining the clinical score with the presence of atypia at cytology we could identify 30 patients (6%) in whom the risk of malignancy was as high as 63%.

CONCLUSIONS

Twenty-five per cent of patients with a cytological result of follicular and Hupsilonrthle cell thyroid lesion had a final diagnosis of malignancy. Only atypia at cytology and spot microcalcifications at thyroid ultrasound were significantly associated with malignancy. Other clinical parameters and thyroid ultrasound patterns can be used to set up a clinical score useful for predicting the individual risk of malignancy before surgery.