Caso
2. Carcinoma timico non organotipico
(WHO
C)
EE
CK34bE12
CD5
CD5
Am J Clin Pathol 1999 Feb;111(2):235-40
Immunoreactivity of a new CD5 antibody with normal
epithelium and malignant tumors including thymic carcinoma.
Tateyama H, Eimoto T, Tada T, Hattori H, Murase T, Takino H.
Department of Pathology, Nagoya City University Medical School, Japan.
CD5, first recognized on subsets of lymphocytes, also is detected in thymic
carcinoma but not in thymoma or other malignant tumors. We studied CD5
expression in 73 cases of malignant tumors of various organs, 22 cases of
thymoma, and 7 cases of thymic carcinoma by immunohistochemistry using the
new monoclonal anti-CD5 antibody, NCL-CD5-4C7, with a pressure cooker
antigen retrieval method. All cases of thymic carcinoma showed positive
staining for CD5, predominantly on the cell membrane. Two of 4 cases of
atypical thymoma also showed focal positivity, whereas the other types of
thymoma were negative. CD5 was detected in cases of malignant tumors other
than squamous cell carcinoma and in the normal epithelium of their
counterparts. Squamous cell carcinomas of various organs were negative for
CD5. Malignant mesothelioma showed peculiar intracytoplasmic staining in
contrast to the other tumors. The NCL-CD5-4C7 positivity in thymic
epithelial tumors may support the hypothesis suggesting progression of
atypical thymoma to thymic carcinoma. NCL-CD5-4C7 may be useful in the
differential diagnosis of mediastinal tumors, especially between thymic
carcinoma and metastatic squamous cell carcinoma of various primary sites,
and for distinguishing malignant mesothelioma from adenocarcinoma of the
lung by the different staining pattern.
Am J Surg Pathol 1997 Aug;21(8):936-40
Thymic carcinomas, but not thymomas and carcinomas of
other sites, show CD5 immunoreactivity.
Dorfman DM, Shahsafaei A, Chan JK.
Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115
Thus far, there are no immunohistochemical markers that are specific for thymic
epithelial neoplasms, although demonstration of immature T cells in an
epithelial tumor can indirectly support a diagnosis of thymoma. In this study,
the usefulness of a paraffin section-reactive CD5 antibody (clone CD5/54/B4) for
supporting the thymic origin of an epithelial neoplasm was evaluated. Antigen
retrieval was effected by microwaving in citrate buffer. Sixteen of 24 thymic
carcinomas (67%) were immunoreactive for CD5, including nine of nine squamous
cell, two of two undifferentiated, two of four lymphoepithelioma-like, and one
case each of basolid carcinoma, clear cell carcinoma, and unclassified thymic
carcinoma, but none of four thymic small cell carcinomas. None of 17 cases of
benign thymoma and 21 cases of invasive thymoma (including six cases
classifiable as well-differentiated thymic carcinoma using the Muller-Hermelink
criteria) was immunoreactive for CD5, in the presence of CD5-positive
lymphocytes as an internal positive control. Two of three thymic neoplasms with
features borderline between thymic carcinoma and invasive thymoma were
immunoreactive for CD5. In contrast, none of 61 cases of other malignant
neoplasms with a tendency to involve the mediastinum was immunoreactive for CD5,
including 40 nonthymic carcinomas and 13 malignant germ cell neoplasma. CD5
staining of thymic epithelial tumors correlated with the absence of
tumor-associated CD99-positive thymocytes, as demonstrated in our previous
studies. We conclude that CD5 is a useful marker of primary thymic carcinomas.
Taken together, CD5 and CD99 (or other immature T-cell markers such as TdT and
Cd1a) should be particularly useful in evaluating mediastinal and other biopsy
samples of possible thymic epithelial neoplasms and in the subtyping of these
tumors.
