ABSTRACT
BACKGROUND: CD99 is a cell surface transmembrane glycoprotein expressed in various tissues. CD99 is differentially expressed between subpopulations of each tissue and is highly expressed in certain hematopoietic and precursor cells. However, there has been no comprehensive study of CD99 expression in normal skin. We evaluated CD99 expression in normal human skin and developing fetal skin. METHODS: Seventy-five adult skin samples containing normal skin and eight fetal skin samples of different gestational ages were collected. CD99 immunohistochemical staining was performed to evaluate expression pattern in adult and fetal skin samples. CD99 and CD34 expression were compared by double immunofluorescence. RESULTS: In normal adult skin, CD99 was strongly expressed in the membrane of epidermal basal keratinocytes, hair follicle bulges and outer root sheaths, and inner secretory cells of eccrine sweat glands. In fetal skin, CD99 was not expressed on the periderm at 16 weeks of gestation but was expressed in basal cells of fetal skin at around 19 weeks of gestation. CD99 expression became comparable to that of the adult skin after 20 weeks of gestation. CD99 and CD34 were co-expressed in hair follicle outer root sheaths, as seen by double immunofluorescence study. CONCLUSIONS: This is the first study examining CD99 expression pattern in normal adult and fetal skin. CD99 tends to be expressed in the basal/precursor cells of epidermis and in hair follicles. These results provide a basis for future investigation on functions of CD99 in the skin and provide a novel potential target for the treatment of dermatologic lesions.
ABSTRACT
BACKGROUND: CD99 is a cell surface transmembrane glycoprotein expressed in various tissues. CD99 is differentially expressed between subpopulations of each tissue and is highly expressed in certain hematopoietic and precursor cells. However, there has been no comprehensive study of CD99 expression in normal skin. We evaluated CD99 expression in normal human skin and developing fetal skin. METHODS: Seventy-five adult skin samples containing normal skin and eight fetal skin samples of different gestational ages were collected. CD99 immunohistochemical staining was performed to evaluate expression pattern in adult and fetal skin samples. CD99 and CD34 expression were compared by double immunofluorescence. RESULTS: In normal adult skin, CD99 was strongly expressed in the membrane of epidermal basal keratinocytes, hair follicle bulges and outer root sheaths, and inner secretory cells of eccrine sweat glands. In fetal skin, CD99 was not expressed on the periderm at 16 weeks of gestation but was expressed in basal cells of fetal skin at around 19 weeks of gestation. CD99 expression became comparable to that of the adult skin after 20 weeks of gestation. CD99 and CD34 were co-expressed in hair follicle outer root sheaths, as seen by double immunofluorescence study. CONCLUSIONS: This is the first study examining CD99 expression pattern in normal adult and fetal skin. CD99 tends to be expressed in the basal/precursor cells of epidermis and in hair follicles. These results provide a basis for future investigation on functions of CD99 in the skin and provide a novel potential target for the treatment of dermatologic lesions.
Subject(s)
Adult , Humans , Pregnancy , Epidermis , Fluorescent Antibody Technique , Gestational Age , Glycoproteins , Hair Follicle , Immunohistochemistry , Keratinocytes , Membranes , Skin , Sweat GlandsABSTRACT
Extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an uncommon, aggressive, and malignant tumor with a poor patient outcome. Its occurrence in the lesser sac is a rare event and to the best of our knowledge, has not been previously described. The present case was clinically and radiologically misdiagnosed as a pancreatic tumor/gastrointestinal stromal tumor. Histopathology revealed a tumor with "small round cells" that were positive for CD99, confirming the diagnosis of ES/PNET. This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.
Subject(s)
Diagnostic Errors , Neuroectodermal Tumors, Primitive, Peripheral/diagnosis , Pancreatic Neoplasms/diagnosis , Peritoneal Neoplasms/diagnosis , Sarcoma, Ewing/diagnosis , 12E7 Antigen , Antigens, CD/analysis , Biomarkers, Tumor/analysis , Biopsy , Cell Adhesion Molecules/analysis , Female , Humans , Immunohistochemistry , Middle Aged , Neuroectodermal Tumors, Primitive, Peripheral/immunology , Neuroectodermal Tumors, Primitive, Peripheral/pathology , Neuroectodermal Tumors, Primitive, Peripheral/therapy , Peritoneal Neoplasms/immunology , Peritoneal Neoplasms/pathology , Peritoneal Neoplasms/therapy , Predictive Value of Tests , Sarcoma, Ewing/immunology , Sarcoma, Ewing/pathology , Sarcoma, Ewing/therapy , Tomography, X-Ray ComputedABSTRACT
Extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an uncommon, aggressive, and malignant tumor with a poor patient outcome. Its occurrence in the lesser sac is a rare event and to the best of our knowledge, has not been previously described. The present case was clinically and radiologically misdiagnosed as a pancreatic tumor/gastrointestinal stromal tumor. Histopathology revealed a tumor with "small round cells" that were positive for CD99, confirming the diagnosis of ES/PNET. This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.
Subject(s)
Female , Humans , Middle Aged , Antigens, CD/analysis , Biopsy , Cell Adhesion Molecules/analysis , Diagnostic Errors , Immunohistochemistry , Neuroectodermal Tumors, Primitive, Peripheral/diagnosis , Pancreatic Neoplasms/diagnosis , Peritoneal Neoplasms/diagnosis , Predictive Value of Tests , Sarcoma, Ewing/diagnosis , Tomography, X-Ray Computed , Biomarkers, Tumor/analysisABSTRACT
Pleomorphic carcinoma of the lung (PCL) is characterized by a mixture of sarcomatoid and carcinoma components, and a poor prognosis. However, no immunophenotype of tumor markers has been characterized in PCL. To charaterize the immunophenotype for CD99 in PCL, we performed an immunohistochemical evaluation of PCLs for thyroid transcription factor-1 (TTF-1), cytokeratin (CK) 7 and 20, and for CD99. CD99 was found to be expressed in both carcinomatous (47%) and sarcomatous components such as spindle cells (92%) and giant cells (57%). In the case of spindle cells, CK7 was expressed in 6 cases (46%) and TTF-1 in 2 cases (15%), whereas for giant cells CK7 was expressed in 8 cases (57%) and TTF-1 in one case (7%). However, CK20 was not expressed in either the carcinomatous or sarcomatous components in any case. Thus, CD99 was found to be widely expressed in both sarcomatous and carcinoma component in PCL. A clinicopathological analysis showed no direct correlation between the expression of CD99 and the clinical indices (stage, survival rate, invasion) of PCL.
Subject(s)
Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Antigens, CD/biosynthesis , Carcinoma/metabolism , Cell Adhesion Molecules/biosynthesis , Immunohistochemistry , Immunophenotyping , Intermediate Filament Proteins/biosynthesis , Keratins/biosynthesis , Lung Neoplasms/metabolism , Nuclear Proteins/biosynthesis , Prognosis , Sarcoma/metabolism , Time Factors , Transcription Factors/biosynthesisABSTRACT
To verify the spectrum of CD99-expressing lymphoid malignancy, an immunohistochemical study for CD99 was carried out in 182 cases of non-Hodgkin's lymphoma, including 21 lymphoblastic lymphomas, 11 small lymphocytic lymphomas, 9 mantle cell lymphomas, 12 follicular lymphomas, 37 diffuse large B cell lymphomas, 18 Burkitt's lymphomas, 28 NK/T-cell lymphomas, 8 angioimmunoblastic T-cell lymphomas, 23 peripheral T-cell lymphomas, unspecified, and 15 systemic anaplastic large cell lymphomas. CD99 was positive in all T-lymphoblastic lymphomas and in 60% of B-lymphoblastic lymphomas. Majority of T and NK cell lymphomas were negative for CD99, except anaplastic large cell lymphomas (ALCLs). Eight of 15 cases (54%) of ALCLs reacted with anti CD99 antibody. Seven of 10 (70%) ALK positive ALCLs expressed CD99, whereas only 1 of 5 (20%) ALK negative ALCLs were positive. Of the mature B-cell lymphomas, 5.4% (2/37) of diffuse large B cell lymphomas and 11.1% (2/18) of Burkitt's lymphomas expressed CD99. In conclusion, CD99 is infrequently expressed in mature B and T cell lymphomas, except ALK-positive ALCL. High expression of CD99 in ALK-positive ALCL is unexpected finding and its biologic and clinical significances have yet to be clarified.
