THYROID

Sonography of thyroid Left lobe : Heterogenous mix echo lesion 15*13 mm Isthmus : mixed echo lesion 8*12 mm Right lobe : normal

poorly differentiated carcinoma Squamous cell carcinoma???!!! Papillary carcinoma Follicular Tall cell Clear cell poorly differentiated carcinoma Squamous cell carcinoma???!!!

papillary cell carcinoma Areas with a solid/trabecular pattern of growth are present in 20% of the papillary carcinoma and foci of squamous metaplasia in a similar number .the presence of such foci is not per se an indication that the tumor is poorly differentiated unless accompanied by other alteration Poorly differentiated squamous or anaplastic foci have a markedly detrimental effect on prognosis. Fortunately, they are present in fewer than 5% of the cases.

Squamous cell carcinoma Squamous cells can be found in the thyroid as' a result of persistence of thyroglossal duct or structures derived from the branchial pouch (such as thymic epithelium) or as an expression of squamous metaplasia in Hashimoto's thyroiditis, papillary carcinoma, or other conditions. Pure squamous cell carcinomas are exceptional.

Squamous cell carcinoma Most high-grade thyroid tumors with squamous foci blend with areas of undifferentiated (anaplastic) carcinoma and are generally placed in the latter category because of their similar natural history. Indeed, many of them are seen to develop from papillary carcinoma in a fashion analogous to that of undifferentiated carcinoma. has been suggested that the tall cell variant of papillary carcinoma has a particular tendency to evolve into the spindle cell type of squamous cell carcinoma.

Squamous cell carcinoma Another rare entity occurring in or around the thyroid that may exhibit squamous differentiation is the malignant neoplasm we have chosen to designate as carcinoma showing thymus-like differentiation (CASTLE). This tumor (of which a cystic variant has been described) could be viewed as an ectopic thymic carcinoma

Squamous metaplasia in papillary carcinoma Or Branchial puoch(thymus)=CASTLE

Support for the thymic rather than thyroidal origin of CASTLE is provided by its immunoreactivity for CD5 CD117 HMWK P63 BCL-2 mcl-1 all of them being markers associated with thymic carcinoma) and negativity for TG and TTF-1.

Immunohistochemically, the cells of papillary carcinoma are reactive for pan-keratin CK7 + / CK20- CK19 HMWK* thyroglobulin and TTF-1 is the rule CEA* CA-125

Carcinoma showing thymus-like differentiation (CASTLE) is a rare intrathyroidal neoplasm, a member of a tumor family probably arising from ectopic thymus or branchial pouch remnants. Thyroid solid cell nests (SCNs) may also be derived from branchial pouch remnants. In normal thyroid, only SCNs stained for p63, HMWK, and CEA. The only CD5-positive cells in normal thyroid were T cells. All CASTLE exhibited diffuse p63 and HMWK staining and were positive for CEA and CD5. In contrast, none of the other thyroid neoplasms exhibited consistent staining for all 4 markers studied. These findings provide further evidence that CASTLE is distinct from other thyroid neoplasms, is probably of thymic origin, and may arise from branchial pouch remnants, the thyroid SCNs. Moreover CD5, HMWK, CEA and p63 can be used to help distinguish CASTLE from other thyroid neoplasms.

We present the case of a 62-year-old woman who consulted her physician in December 2009, suffering from a mass at the left lower anterior neck with rapid enlargement. Intraoperative frozen section was highly suspicious of a CASTLE tumour (carcinomas showing thymus-like differentiation). Finally, immunohistochemical investigation revealing positivity for CK5/6, c-kit (CD117) and CD5 as well as negativity for thyroglobulin, calcitonin, vimentin and TTF-1 confirmed the diagnosis.

Papillary: Squamous: TTF-1 : + TG : + CD5 : - Papillary carcinoma CASTLE عنوان:

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