LETTER TO EDITOR
Year : 2009 | Volume
: 52 | Issue : 4 | Page : 577--579
Synchronous papillary thyroid carcinoma with mucinous rectal carcinoma
SG Barreto1, T Shet2, SV Shrikhande1, PJ Shukla1,
1 Department of Gastrointestinal Surgical Oncology, Tata Memorial Hospital, Mumbai, India
2 Department of Pathology, Tata Memorial Hospital, Mumbai, India
P J Shukla
Department of Gastrointestinal Surgical Oncology, Tata Memorial Hospital Parel, Mumbai 400 012
|How to cite this article:|
Barreto S G, Shet T, Shrikhande S V, Shukla P J. Synchronous papillary thyroid carcinoma with mucinous rectal carcinoma.Indian J Pathol Microbiol 2009;52:577-579
|How to cite this URL:|
Barreto S G, Shet T, Shrikhande S V, Shukla P J. Synchronous papillary thyroid carcinoma with mucinous rectal carcinoma. Indian J Pathol Microbiol [serial online] 2009 [cited 2021 Nov 30 ];52:577-579
Available from: https://www.ijpmonline.org/text.asp?2009/52/4/577/56122
Metastasis from colorectal cancers to the thyroid gland is extremely rare with a 4% incidence from autopsy data.  The possibility of a dual malignancy is extremely rare even in the presence of a positive family history.  We report such a rare occurrence of dual malignancy of the thyroid and rectum in order to stress the importance of a good preoperative workup to arrive at such a diagnosis preoperatively and also to stress the importance of radical curative surgery in patients with a good general condition with operable primary tumors.
A 51-year-old male presented to us with a history of constipation and bleeding per rectum. General examination revealed a swelling in the neck that moved with deglutition suggestive of a swelling arising from the thyroid. The left supraclavicular node was felt hard and mobile. Per rectal examination revealed a circumferential growth in the anorectum starting from the anal verge with restricted mobility. There was no luminal compromise. A proctoscopic biopsy confirmed the diagnosis of signet ring cell adenocarcinoma. Colonoscopy ruled out synchronous polyps or malignancies in the rest of the visualized colon. Serum carcinoembryonic antigen (CEA) level was 5.08 ng/ml. A computed tomography of the abdomen and pelvis confirmed rectal malignancy with perirectal fat stranding. A fine needle aspiration of the thyroid swelling and the supraclavicular lymph node revealed a papillary adenocarcinoma of the thyroid with metastasis to the lymph node. A positron emission tomography with computed tomography (PET-CT) of the whole body was performed that confirmed active disease in the rectum and the right paratracheal region in neck abutting the lower pole of right lobe of thyroid and active disease in the supraclavicular lymph node. In view of the locally advanced nature of the rectal growth, the patient was advised neoadjuvant radiotherapy. After completion of the radiotherapy, the patient underwent an abdominoperineal resection with total thyroidectomy with bilateral modified radical neck dissection. The patient had a smooth postoperative recovery and was discharged on the ninth postoperative day. His final histopathology confirmed a poorly differentiated signet ring adenocarcinoma of the rectum (T3) with negative regional nodes [Figure 1] with a well-differentiated papillary carcinoma of the thyroid with metastatic regional lymph nodes [Figure 2]. The patient is now undergoing radioiodine 131 for the papillary carcinoma and chemoradiation for the rectal cancer.
Despite a thorough Pubmed search [with the keywords - papillary, thyroid carcinoma, synchronous, simultaneous, rectal cancer], we were unable to find a previously reported sporadic case of synchronous or simultaneous papillary thyroid carcinoma and signet ring rectal adenocarcinoma.
The likelihood of dual malignancies in this patient was confirmed preoperatively by a combination of fine needle aspiration cytology of the thyroid and supraclavicular nodes and a biopsy from the rectal growth. The absence of familial adenomatous polyposis was determined after a complete colonoscopy failed to reveal any other colorectal pathology in addition to the rectal growth. PET-CT imaging helped in confirming the absence of distant metastasis from either of the malignancies. This, coupled with the good general condition of the patient, enabled us to plan a radical curative surgery for the patient.
In order to explain the molecular basis for such an occurrence, we reviewed the existing literature. The probability of an underlying germline mutation of a tumor-suppressor gene as an initiating event that may interact with mutant K-ras (a somatic mutation) was put forth by Kadam et al.  Kimura et al.  detected a high prevalence of BRAF mutations in papillary thyroid cancers. Most papillary thyroid carcinomas with BRAF mutations have a classical histology. Li et al.  found a strong association between BRAF mutations and poor grade, mucinous rectal neoplasms. While Yuen et al.  found that although colorectal adenocarcinomas with BRAF mutations are associated with early Dukes' tumor stages, the presence of the mutation does not impact differentiation or morphology. Interestingly, the BRAF mutations are more frequently found in sporadic rather than familial colorectal adenocarcinomas. In our patient, it was interesting to note that the rectal cancer was poorly differentiated while the thyroid cancer was well-differentiated.
In the light of these recent advances in molecular biology we can only conjecture that the BRAF somatic mutation which has been found in both papillary thyroid cancers and colorectal cancers may be one such putative mutation underlying such an occurrence.
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