|LETTER TO THE EDITOR
|Year : 2016 | Volume
| Issue : 4 | Page : 549-550
Cytomorphology of insular carcinoma thyroid: A diagnostic dilemma
Jayanti Mehta1, Deepti Sukheeja2
1 Department of Pathology, SMS Medical College, Jaipur, Rajasthan, India
2 Department of Pathology, Government Medical College and Associated Group of Hospitals, Kota, Rajasthan, India
|Date of Web Publication||12-Jul-2016|
C/O Mr. O. P. Sukheeja, 1, Vigyan Nagar Special, Near P and T Colony, Vigyan Nagar, Kota - 324 005, Rajasthan
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mehta J, Sukheeja D. Cytomorphology of insular carcinoma thyroid: A diagnostic dilemma. Med J DY Patil Univ 2016;9:549-50
Carcangiu et al., in 1984 described a new thyroid neoplasm that had intermediate characteristics between well-differentiated and anaplastic thyroid carcinoma in respect to its morphologic, biologic, and clinical behavior. This neoplasm has not been found to be rapidly or uniformly fatal, but it is distinguished by its greater propensity for local recurrence and distant metastatic behavior than do the well-differentiated thyroid carcinomas.,, The insular carcinoma of the thyroid is difficult to diagnose on cytology due to its overlapping features of various follicular neoplasms of the thyroid. Herein, we describe a case of insular carcinoma of the thyroid and describe its salient cytologic features.
A 60-year-old female presented with dysphagia and gradually enlarging neck mass. On physical examination, there was enlarged, diffusely nodular thyroid gland. There was no cervical lymphadenopathy. Routine hematological parameters and thyroid profile was normal.
Fine needle aspiration cytology (FNAC) was of the enlarged thyroid was done. Smears were prepared and stained with hematoxylin and eosin. The FNAC, in this case, displayed abundant monomorphic follicular cells present singly, in small loose aggregates and in cohesive, three-dimensional clusters (representing of insulae) with scanty colloid.
The cytosmears showed high cellularity. Cells displayed fragile, ill-defined, and granular cytoplasm. The nuclear: Cytoplasmic ratio was high. Tumor cells showed round and monomorphic nuclei, coarse, clumped chromatin prominent nucleoli. Necrosis and mitosis were rare [Figure 1]. There were no intranuclear inclusions or grooving. The case was diagnosed as poorly differentiated carcinoma of insular type.
|Figure 1: Cytosmears showing cells in syncytial (three-dimensional) cluster with cells showing high nuclear: Cytoplasmic ratio with coarse clumped chromatin (H and E, ×400)|
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Total thyroidectomy done and the case was confirmed on histopathology as insular carcinoma. The tumor cells were arranged in nests enveloped by a well-developed capillary framework. A tumor composed of round cells with evenly distributed nuclear chromatin and inconspicuous nucleoli [Figure 2].
|Figure 2: Tissue section showing follicular cells arranged in insular pattern (H and E, ×100)|
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The cytologic diagnosis of insular carcinoma of the thyroid is difficult as reported series have been small because of its rare occurrence. Walczyk et al. found the incidence of insular carcinoma at 1.75% in a series 801 patients of thyroid carcinomas. The literature consists of retrospective reviews of the aspirates after the histologic diagnosis had been made from the thyroidectomy specimens. Also, the case reports do not provide uniform cytologic criteria; this could be due to limited sampling of these tumors.
A cytologic diagnosis of insular carcinoma can be suggested if multiple samples of a thyroid mass are markedly cellular with abundant cohesive and dyshesive monomorphic follicular cells in three-dimensional clusters. Sometimes endothelium wrapping around cell groups are present in the tumor FNAC representing the insular arrangement of cells. Intranuclear cytoplasmic inclusions, nuclear grooves and microfollicles having dense colloid  have been reported in some cases but was not seen in our case. Barwad et al. has done a study on ten cases of which three showed inspissated colloid.
The common differential diagnosis is papillary and medullary carcinoma of small cell type. Nuclear features, positive immunostaining for thyroglobulin and negative for calcitonin in the cells of insular carcinoma is helpful in differentiating such cases.
Cytological diagnosis of insular carcinoma should be considered whenever highly cellular smears showing monomorphic cells with three-dimensional crowding is seen. The knowledge of the distinctive cytomorphological appearance of insular carcinoma would enable early and correct identification of these lesions and thereby prompt institution of treatment.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]