Cytomorphologic features of diffuse sclerosing variant of papillary carcinoma of the thyroid. A report of two cases in children

Cytologic features of aggressive variants of follicular-derived thyroid carcinoma

Certain carcinomas of the thyroid gland behave aggressively resulting in increased patient morbidity and poor patient prognosis. The diagnosis of these aggressive thyroid cancer subtypes is sometimes challenging and subject to increased interobserver variability. This review deals with the cytological features of such tumors including aggressive variants of papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. These malignancies fall into 2 groups based on their cytomorphology: those that exhibit distinct microscopic features (eg, nuclear findings typical of classical papillary thyroid carcinoma or marked anaplasia) and those that present with more subtle cytologic features (eg, nuclear pseudostratification, "soap bubble" nuclei, supranuclear or subnuclear cytoplasmic vacuoles, rosette-like structures, hobnail cells). We review the literature regarding these aggressive thyroid cancers and highlight important phenotypic characteristics that can be useful for their diagnosis based on fine needle aspiration.

Bethesda classification is a valuable guide for fine needle aspiration reports and highly predictive especially for diagnosing aggressive variants of papillary thyroid carcinoma

BACKGROUND

A fine needle aspiration biopsy (FNAB) is the most valuable diagnostic procedure for pre-operative discrimination of benign and malignant nodules. The Bethesda System for Reporting Thyroid Cytopathology provides standardised reporting and cytomorphological criteria in aspiration smears. The aim of the present study was to determine malignancy rates in nodules with different cytology results and evaluate the diagnostic value of Bethesda for variants of papillary thyroid carcinoma (PTC).

MATERIALS AND METHODS

A retrospective analysis of 2534 cases with 5784 thyroid nodules, who underwent FNAB followed by surgery, were included in this study. FNAB was performed with ultrasonography guidance. Cytological diagnoses were classified as: non-diagnostic (ND), benign, atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), suspicious for malignancy (SUS) and malignant. Histopathological diagnoses were classified into four groups: benign, PTC, follicular thyroid cancer and other types of thyroid cancer (including medullary thyroid cancer, undifferentiated thyroid cancer and thyroid tumours of uncertain malignant potential). Cases with PTC were further divided into four categories: conventional variant, follicular variant, aggressive variants (tall cell, diffuse sclerosing and columnar variant) and other variants (oncocytic, solid/trabecular and warthin-like variants). FNAB results were compared with histopathological results.

RESULTS

Malignancy rates were 6.3%, 3.2%, 20.7%, 33.3%, 74.2% and 95.6% in the nodules with ND, benign, AUS/FLUS, FN/SFN, SUS and malignant cytology results, respectively. Pre-operative cytology was malignant or SUS in 56.6% of conventional, 24.3% of follicular, 92% of aggressive and 41.7% of other variants of histopathologically confirmed PTC. The difference between the groups was significant (P < 0.001).

CONCLUSION

The Bethesda classification is a reliable indicator of malignancy in nodules with different cytology results and seems to be very effective in predicting the malignancy for the nodules diagnosed with aggressive variant PTC on the final histological examination.

A Case Report Demonstrating How the Clinical Presentation of the Diffuse Sclerosing Variant of Papillary Thyroid Carcinoma Can Mimic Benign Riedel's Thyroiditis

A 44-year-old female presented with a two-month history of a neck mass, sore throat, hoarseness, and intermittent dysphagia. Examination revealed a "woody" hard swelling arising from the right lobe of the thyroid. Clinically this was felt to be classical Riedel's thyroiditis (RT). Thyroid ultrasound showed a diffusely enlarged, low echogenicity thyroid with a multinodular goitre. An abnormal nodule extending across the isthmus was noted. Following a nondiagnostic fine needle aspiration, an open core biopsy was performed. This showed dense sclerotic fibrosis punctuated by nodular mononuclear inflammatory cells, which obscured follicular epithelial cells consistent with a fibrosing thyroiditis (Riedel's thyroiditis). A biopsy of pretracheal lymph nodes showed a sclerotic process throughout the lymph nodes and nests of epithelium bands with squamous differentiation obscured by a fibrous process. These findings raised the differential diagnosis of diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) with metastasis to lymph nodes. A total thyroidectomy and pretracheal lymph node dissection were performed. The final histological diagnosis was DSV-PTC. When managing a patient with presumed RT it is important to consider malignancy in the differential. DSV-PTC is one of the more aggressive forms of thyroid cancer but with early diagnosis and appropriate treatment patients may have excellent outcomes.

Diffuse sclerosing variant of papillary thyroid carcinoma: a study of fine needle aspiration cytology in 20 patients

BACKGROUND

A diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) is a rare variant and reports describing the cytological findings are few.

PATIENTS AND METHODS

We studied 24 cytological samples from thyroid fine needle aspirates of 20 patients with DSV-PTC. The specimens were taken from 14 non-nodular lesions and 10 nodules.

RESULTS

All aspirates taken from both non-nodular lesions and nodules had sufficient cellularity. The carcinoma cells frequently (70-100%) appeared as solid cell balls and hollow balls, and showed a hobnail pattern, squamous differentiation, septate cytoplasmic vacuoles and large unilocular vacuoles. Most of the carcinoma cells seem to be taken from the lumen of dilated lymph vessels. Ground glass nuclear chromatin, intranuclear cytoplasmic inclusions and grooved nuclei were infrequent (50% or less). In the background, a large number of lymphocytes and abundant psammoma bodies were almost always seen.

CONCLUSIONS

Cytological findings of DSV-PTC are as follows: (1) solid cell balls and/or hollow balls containing lymphocytes; (2) hobnail cells; (3) septate cytoplasmic vacuoles; (4) large unilocular vacuoles; (5) squamous differentiation; (6) abundant psammoma bodies; (7) lymphocytic background; and (8) the absence or relative lack of characteristic nuclear features of papillary carcinoma. When DSV-PTC is suspected by ultrasound examination, the aspiration cytology from a non-nodular area of the thyroid can led us to the diagnosis of the variant.

Diffuse sclerosing variant of thyroid papillary carcinoma: diagnostic challenges occur with Hashimoto's thyroiditis

Diffuse sclerosing papillary thyroid carcinoma (DSPTC) is a relatively rare variant of papillary thyroid carcinoma with distinct histological features, radiological characteristics, and biological aggressiveness. Compared with conventional papillary thyroid carcinoma, DSPTC is characterized by scattered microscopic tumor islands, diffuse fibrosis, calcification, and abundant lymphocytic aggregation. A preoperative diagnosis is challenging in the absence of nodules and scanty fine needle aspiration cytology samples. We describe a unique DSPTC patient, an 18-year-old woman who presented with a neck mass that grew slowly for 2 years. The palpable neck mass was nontender, well defined, firm, and unmovable. Laboratory studies showed normal thyroid function and positive autoimmune markers: antithyroglobulin antibody = 1:1600 and antimicrosomal antibody = 1:1600. A neck ultrasound showed diffusely prominent microcalcifications with one small vague nodule. Hashimoto's thyroiditis with an accompanying malignancy was suspected. Based on the result of intraoperative pathology reports, the patient was given a total thyroidectomy. Lymph node dissection and histological analysis revealed bilateral DSPTC in addition to lymphocytic thyroiditis in nonmalignant areas of the thyroid. Clinical and histological diagnostic challenges usually occur when DSPTC presents with a diffuse thyroid enlargement, dispersed microscopic tumor islands (frequently without mass formation), extensive fibrosis, and abundant lymphocytic infiltration mimicking thyroiditis.

Diffuse sclerosing variant of papillary carcinoma of the thyroid: ultrasound features with histopathological correlation

AIM

To evaluate the ultrasound (US) features of the diffuse sclerosing variant of papillary carcinoma (DSVPC) of the thyroid, with histopathological correlations.

MATERIALS AND METHODS

The US and histopathological findings of six patients with surgically proven DSVPC of the thyroid were retrospectively assessed.

RESULTS

Most of cases showed diffuse, scattered microcalcifications with or without associated masses and underlying heterogeneous hypoechogenicity at the site of the DSVPC in the thyroid. At ultrasound, scattered microcalcifications and heterogeneous hypoechogenicity seen in the DSVPC correlated to psammoma bodies and lymphocytic infiltration at histopathological review.

CONCLUSION

DSVPC of the thyroid usually manifested as diffuse scattered microcalcifications and associated suspicious mass on ultrasound. These findings are not specific for the DSVPC of the thyroid. However, in relatively young patients with suspicious masses associated with underlying diffuse scattered microcalcifications on US, the possibility of DSVPC should be included in differential diagnosis.

Diffuse Sclerosing Variant of Papillary Carcinoma of the Thyroid: A 35-Year Comparative Study at a Single Institution

BACKGROUND

Diffuse sclerosing variant (DSV) is a rare variant of papillary thyroid carcinoma (PTC), and the features of this carcinoma have not been fully characterized. The aim of this study was to analyze the clinicopathologic features of a large cohort of patients with this disease.

METHODS

We reclassified primary thyroid carcinomas treated in a 35-year study period and studied the clinicopathologic features and outcomes of DSV of PTC in comparison with classic PTC.

RESULTS

Fifteen patients (2 men and 13 women) with DSV of PTC were identified who had surgical resection of the thyroid. Fine-needle aspiration biopsy diagnosed 83% (10 of 12) of the tumors. Compared with classic PTC, patients with DSV presented at a younger age (mean age, 29 vs. 46 years; P = .0001), had larger tumors (mean diameter, 3.6 vs. 2.2 cm; P = .002), and had a higher incidence of cervical nodal metastases (80% vs. 43%; P = .006). Ten patients had received postoperative iodine 131 ablation, and four had also received external-beam irradiation. Distant metastases were detected in two patients (one in lung and one in brain). One third (5 of 15) of the patients developed disease recurrence. Lymph node recurrence was detected in one patient 12 years after the initial operation. Over a median follow-up period of 10.7 years, one patient with an initial incomplete excision died of the carcinoma. The overall disease-specific survival rate was 93%.

CONCLUSIONS

DSV of PTC had distinctive clinicopathologic features and a high incidence of recurrence after operation but had a prognosis similar to that of classic PTC.

Fine-needle aspiration of the thyroid: an overview

Thyroid nodules (TN) are a common clinical problem. Fine needle aspiration (FNA) of the thyroid now is practiced worldwide and proves to be the most economical and reliable diagnostic procedure to identify TNs that need surgical excision and TNs that can be managed conservatively. The key for the success of thyroid FNA consists of an adequate or representative cell sample and the expertise in thyroid cytology. The FNA cytologic manifestations of TNs may be classified into seven working cytodiagnostic groups consisting of a few heterogenous lesions each to facilitate the differential diagnosis. Recent application of diagnostic molecular techniques to aspirated thyroid cells proved to be useful in separating benign from malignant TNs in several cases of indeterminate lesions.

Diffuse sclerosing variant of papillary thyroid carcinoma: a clinicopathologic and immunophenotypic analysis of 22 cases

BACKGROUND

The diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) is an uncommon tumor making up about 2% of all papillary thyroid carcinomas. Previous studies have not comprehensively evaluated these tumors in a large series of patients.

DESIGN

Twenty-two cases of DSV-PTC diagnosed between 1970 and 2000 were identified in the files of the AFIP. Histologic and immunohistochemical features were evaluated and patient follow-up was obtained.

RESULTS

The tumors affected 14 females and 8 males, aged 6 to 49 yr (mean, 18 yr), with males presenting at a mean older age than females (24 vs 14 yr). Symptoms included an enlarging mass in the thyroid, present for a mean of 9.5 mo. While a dominant tumor was identified in a single lobe, bilateral disease was common (n = 16). The dominant mass ranged in size from 1.7 to 5.8 cm in diameter (mean, 3.8 cm). Histologically, all cases demonstrated a papillary carcinoma (conventional, solid, or follicular pattern) diffusely involving the gland. Extrathyroidal extension, lymphocytic thyroiditis, squamous metaplasia, increased fibrosis/sclerosis, and psammoma bodies were present to a variable degree. Both the papillary carcinoma and squamous metaplasia cells were strongly immunoreactive with CK19, thyroglobulin, and TTF-1. An increased number of S-100 protein immunoreactive dendritic cells were recognized. p53 was increased (>15%) in the tumor cells in 12 patients, while Ki-67 was increased in the tumor cells in two patients. Perithyroidal and cervical lymph node metastasis occurred in 18 (82%) patients. All metastases demonstrated histologic features similar to the primary. Complete resection (thyroidectomy in 18 patients) with lymph node dissection, yielded a 95% 5-yr survival without evidence of disease. One patient died of disease after a malignant transformation of the squamous metaplasia into squamous cell carcinoma.

CONCLUSIONS

The recognition of DSV-PTC can be made with the following features: classic to solid foci of PTC, lymphocytic thyroiditis, squamous metaplasia, increased fibrosis, and innumerable psammoma bodies. DSV-PTC is more biologically aggressive than conventional PTC, but the patients' survival is not significantly different. This diagnosis should lead the clinician to aggressively manage these patients (thyroidectomy and lymph node dissection) in an effort to achieve an excellent long-term clinical outcome.

Diffuse Sclerosing Variant of Papillary Thyroid Carcinoma

Diffuse sclerosing variant of Papillary Thyroid Carcinoma(DSPC) is an unusual type of Papillary Carcinoma that occurs in young patients. Clinically it can be mistaken for Hashimoto's Thyroiditis as it often presents as a diffuse firm thyroid swelling 3*. It is important to recognize this variant as the patients invariably have lymph node metastasis at the time of diagnosis.Contrary to the previous reports of a poor prognosis of this variant when compared to the classical papillary carcinoma, recent reports indicate a good prognosis(2,3). We report a case of DSPC occurring in a young boy.

Thyroid spindle epithelial tumor with thymus-like differentiation (SETTLE): is cytopathological diagnosis possible?

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare tumor of the thyroid gland which occurs predominantly in children, adolescents, and young adults. It usually presents as a painless neck or thyroid mass and only exceptionally as a diffusely enlarged thyroid gland, without metastatic disease at diagnosis. We report on the case of 12-yr-old girl who had diffusely enlarged thyroid gland for about 1 yr and was initially treated for thyroiditis. Fine-needle aspiration biopsy (FNAB) was performed 8 mo after the first admission. Cytological examination of smears showed unusual morphological features. FNAB smears were cellular, with dissociated cells, naked oval nuclei, aggregates, and groups. Three main cell types were observed: spindle, epithelioid, and epithelial. These cells were uniform, cytologically bland, with few mitotic figures. The distinction between these cells was not always unequivocal. In the background of the smears abundant red extracellular material in the form of fine, dust-like granules and irregular patches were present. It was also observed in some aggregates and groups of tumor cells. Spindle and epithelioid cells were immunocytochemically diffusely pan-cytokeratin-positive. In the differential diagnosis, medullary thyroid carcinoma and SETTLE were suggested. The final histological diagnosis was SETTLE. In cases of SETTLE presented as a diffuse thyromegaly the correct diagnosis may be delayed because clinically and ultrasonographically thyroiditis is suspected. To avoid such a delay, FNAB should be used preoperatively. It can provide specific cytological diagnosis based on morphological features and certain immunocytochemical characteristics of the tumor.