Poorly differentiated thyroid carcinoma: a retrospective clinicopathological study

Abstract

Poorly differentiated thyroid carcinoma (PDTC) is an independent thyroid cancer histotype. In spite of its scarcity, it represents the main cause of death from non-anaplastic follicular cell-derived thyroid cancer. However, given the newness of this entity, few data are available on its clinical behaviour and no explicit consensus sets its treatment. To report the experience of a tertiary medical centre in morocco with PDTC over a period of 7 years. Retrospective study selecting all patients treated for thyroid carcinoma in Nuclear Medicine Department of a tertiary medical centre in Casablanca over seven years period. Patient's files were reviewed for background data, clinico-pathological characteristics, treatment and outcome. Seven patients were included in the study. Patient's average age was 60 years old (30-81) including six women and one man. All patients underwent a total thyroidectomy completed by cervical lymph node dissection in 57% of cases. Mean primary tumour size was 4cm (1-9cm). Patients were classified pT3 in 70% of cases, pT1 and pT2 in 15% each. Vascular invasion was found in 85% of cases. Pathological subtypes found were “insular carcinoma” in 85% of cases. Radioiodine therapy (RIT) was indicated in all cases. Follow-up period ranged between 10 months and 6 years. It showed a complete remission in 57% of cases, persistent disease in 28% of cases and a progressive disease in 15% of cases with a local recurrence. To date, the survival rate is 85%. PDTC is an aggressive thyroid cancer histotype. Treatment remains surgical followed by RIT if the tumour is radioavid. Multimodality therapy is indicated depending on the case and close monitoring is always indicated given the high risk of relapse.

A Report About a 23-year-old Young Mother Suffering From Rare Insular Thyroid Carcinoma

“…It is an independent type of thyroid cancer and its biological behavior is between well-differentiated and anaplastic thyroid cancer. The condition is commonly seen in women between 46-52 years old and more than 50% of them are over 50 years old, younger patients are less commonly affected [2] . It is generally believed that insular thyroid carcinoma originates from thyroid follicular cells, but Lam [3] suggests that that well-differentiated cancer may gradually progress to insular thyroid carcinoma.…”

Poorly differentiated thyroid cancer in the context of the revised 2015 American Thyroid Association Guidelines and the Updated American Joint Committee on Cancer/Tumor‐Node‐Metastasis Staging System (eighth edition)

“…Poorly differentiated thyroid cancer (PDTC) represents a rare and heterogeneous group of malignant tumours that originate from thyroid follicular cells . The incidence rate of PDTC is 0.23% in North Africa, accounting for 2%‐3% of all thyroid cancers (TCs); the incidence rate is 6.7% in Northern Italy, although a prevalence rate of 15% was reported previously in this area . Although clinical studies on PDTC are limited because of the relative rarity of the disease, the aggressive nature and poor prognosis of this type of TC in contrast to with well‐differentiated thyroid cancer (WDTC) have been demonstrated .…”

“…Because of its aggressive features, PDTC is the main cause of death from non‐anaplastic follicular cell‐derived TC . Despite this fact, the recently adopted AJCC/TNM staging system does not include a separate provision for PDTC, and the same staging system is used for WDTC and PDTC .…”

“…1,2 The incidence rate of PDTC is 0.23% in North Africa, accounting for 2%-3% of all thyroid cancers (TCs); the incidence rate is 6.7% in Northern Italy, although a prevalence rate of 15% was reported previously in this area. 1,[3][4][5][6] Although clinical studies on PDTC are limited because of the relative rarity of the disease, the aggressive nature and poor prognosis of this type of TC in contrast to with well-differentiated thyroid cancer (WDTC) have been demonstrated. 1,4,[7][8][9] In 2004, for the first time, the World Health Organization (WHO) classified PDTC as a separate type of TC according to its distinct morphological and behavioural characteristics, placing it in an intermediate position between WDTC and fully de-differentiated anaplastic TC.…”

“…Because of its aggressive features, PDTC is the main cause of death from non-anaplastic follicular cell-derived TC. 1,3,6,7 Despite this fact, the recently adopted AJCC/TNM staging system does not include a separate provision for PDTC, and the same staging system is used for WDTC and PDTC. 13 The recent ATA criteria for risk stratification define PDTC as an aggressive histological variant of DTC based on estimation of prognosis, suggesting that PDTC patients should be evaluated at least as intermediate risk (IR) TC patients.…”