Thyroid collision tumor containing oncocytic carcinoma, classical and hobnail variants of papillary carcinoma and areas of poorly differentiated carcinoma

Abstract

Collision tumors are rare and may comprise components with different behavior, treatments, and prognosis. We report an unprecedented case of aggressive thyroid collision tumor containing widely invasive oncocytic carcinoma (OC), classical and hobnail (HPTC) variants of papillary carcinoma, and poorly differentiated carcinoma (PDTC). The patient underwent total thyroidectomy, radioactive iodine therapy, and within months progressed with local recurrence, and pulmonary metastases requiring neck dissection, external radiotherapy and systemic treatment with sorafenib. The rapid progression, dedifferentiated metastatic lesions, and failure to treatments resulted in the patient´s death. The great variety of histological types and the evolution of this case were a challenge for the management of metastatic disease. Widely invasive OC, HPTC and PDTC are considered to have a worse prognosis. HPTC has never been reported as a component of a collision tumor. HPTC and PDTC should call attention to a possible higher-grade transformation.

Clinicopathological features and prognostic factors analysis of multiple synchronous distinct subtypes of primary thyroid carcinoma

“…Since the pathogenesis of the coexistence of two tumors of different origins in the same thyroid gland is unclear, various hypotheses have been proposed to explain this phenomenon, including the stem cell theory, the random collision effect theory, and the theory that one tumor induces another tumor [8,9,21,22] .The collision effect theory states that tumors are composed of two distinct, separate components. The authors supporting this theory have proposed the term "collision tumor" to refer to these tumors, and our patients mostly have this form-two tumors separated by normal thyroid tissue [23] .Consistent with the Gurkan report [23] the presence of mixed thyroid carcinoma seems to support the stem cell theory.…”

“…The results showed that the age of SDDTC was younger than that of SMDTC and SADTC, and the average age at diagnosis of SADTC was the largest, followed by SMDTCr, which was similar to the age analysis results of singleton thyroid cancer [31][32][33] .There was no statistically significant gender difference among the three groups，SADTC not only has a longer maximum tumor diameter than SDDTC and SMDTC, but also has a significantly longer disease duration than SDDTC and SMDTC, previously reported that anaplastic carcinoma is highly aggressive, progresses rapidly, and the neck mass expands rapidly [34] .However, the SADTC in our case has a longer course of disease, up to 20 years. There are existing reports on SADTC and the course of the disease are also more than 20 years [9,12] , may be due to undifferentiated progression from differentiated [35] .…”

“…Hao Li and Jie Zhou reported cases in which lymph node recurrence and distant metastasis of SMDTC were treated with surgery for recurrence and metastasis, respectively, and good curative effects were obtained [47,48] , there are also case of radiotherapy for distant metastases of SDDTC without surgery to achieve good prognosis [16] . However, Marcos reported that a case of SADTC recurrence was still ineffective after surgery and progressed rapidly and died [9] .Of 21 patients with recurrence or metastasis, 5 underwent surgery for recurrence or metastasis and 16 did not undergo reoperation. There was no statistically significant difference in the prognosis of recurrence or metastases with or without reoperation, which may be related to the lack of data we included and the choice of the timing of reoperation, or even the combination of different pathological types.…”

“…Such reports have aroused extensive discussion, and since then, the coexistence of multiple different types of thyroid cancer has gradually been reported and recognized. To date, the cases of synchronous squamous cell carcinoma of thyroid(SCCT), papillary(PTC), follicular(FTC), medullary(MTC), poorly differentiated(PDTC) and anaplastic(ATC) thyroid carcinomas have been reported, and both coexisting forms of thyroid cancer have also been implicated [5,[8][9][10][11][12] . However, due to factors such as rare cases and limited conditions, there are few clinical studies on the clinicopathological characteristics and prognosis of multiple synchronous, distinct subtypes of primary thyroid carcinoma.…”

A unique case of anaplastic thyroid carcinoma comprising of two distinct patterns osteoclastic variant and squamous cell carcinoma in separate lobe imitating collision tumor: A case report

“…This case imitates the criteria of collision tumor due to two different cytomorphology with no intermixing occurring in two separate thyroid lobes. Though many hypotheses have been proposed for the development of collision tumors, however most widely accepted are (1) stem cell theory, (2) random collision effect theory, (3) common genetic behavior and (4) one tumor predisposing the other tumor theory 4 . Collision tumor is distinct from mixed tumor which have common cellular origin as well as from composite tumors in which same driving mutation leads to histologically different cellular population in the same tumor 5 .…”