Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Merkel cell carcinoma is an uncommon aggressive primary cutaneous neuroendocrine carcinoma. Histologically, the differential diagnosis includes the 'small round cell' tumor group, particularly metastatic small cell carcinoma and blastic hematological malignancies involving skin/soft tissues. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase, which is a sensitive and specific antibody for acute lymphoblastic lymphoma with a small proportion of acute myeloid leukemia showing positivity. This study investigates the expression of TdT in 20 cases with initial diagnosis of Merkel cell carcinoma. Archival blocks and slides were retrieved and reviewed and clinical information obtained from patient charts. Immunohistochemistry was performed and graded as: 0, no staining; 1+, less than 50% staining in the cells; 2+, 50% or more staining in the cells. After review, 15 cases were confirmed as Merkel cell carcinoma. Immunohistochemical positivity was as follows: 8/15 cases were positive for TdT with strong nuclear staining, morphologically resembling 'blasts', AE1AE3, CAM5.2 (15/15) (both membrane and paranuclear dot positivity), CD56 and BCL-2 (15/15), Synaptophysin (13/15), Chromogranin A (11/15), NSE (15/15), CK20 (14/15), CK7 (3/15), both CK7 and CK20 (3/15), CD117 (8/15), CD99 (2/15), CD10 (1/15). One case was negative for CK7/CK20. All 15 cases were negative for thyroid transcription factor-1, LCA, CD20, CD3 and CD34. Expanded immunohistochemical panel with positive staining for epithelial/neuroendocrine markers, CK20, negative staining for hematolymphoid markers and awareness of TdT expression and other markers that show overlap with blastic hematological malignancies avoids misinterpretation in the diagnosis of Merkel cell carcinoma. This aids in further diagnosis of Merkel cell carcinoma, avoiding the potential diagnostic pitfall with other small round cell tumors and hematological malignancies primary or metastatic to the skin.
 ...
PMID:TdT expression in Merkel cell carcinoma: potential diagnostic pitfall with blastic hematological malignancies and expanded immunohistochemical analysis. 1788 74

Merkel cell carcinoma (MCC) is a high-grade neuroendocrine carcinoma of skin characterized by cells with a "blastic" appearance, scant cytoplasm, and fine, evenly distributed chromatin. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase present in thymic T cells, lymphoblastic lymphoma/leukemia, and some cases of acute myeloid leukemia. After observing TdT immunoreactivity in a case of MCC, we analyzed 26 tumors by immunohistochemical analysis to determine their spectrum of reactivity with TdT and identified TdT in 19 (73%) of 26 MCCs. Staining intensity was variable but was often moderate to strong and present in a significant percentage of cells. Because MCC has cytomorphologic features similar to those of lymphoblastic lymphoma and may manifest as metastatic disease, reactivity with TdT in MCC could represent a diagnostic pitfall in the differential diagnosis with lymphoblastic lymphoma, particularly because the latter may lack CD45 and/or CD20, yet both neoplasms may express PAX-5, a B-cell-associated marker.
 ...
PMID:Reactivity with TdT in Merkel cell carcinoma: a potential diagnostic pitfall. 1848 5

Combination of the splenic marginal zone B-cell lymphoma (SMZL) and classical Hodgkin lymphoma (cHL) is extremely rare. We report a unique case with concurrent SMZL and cHL. The patient was a 63-year-old man who presented with fatigue and anemia, showing a splenomegaly and retroperitoneal lymphadenopathy. A splenectomy revealed monotonous marginal zone lymphocytic infiltrates and numerous large Reed-Sternberg-like cells. Flow cytometry revealed a kappa light-chain-restricted CD5 (-), CD23 (-) B-cell population. DNA polymerase chain reaction analysis confirmed the presence of clonal rearrangement of the immunoglobulin heavy-chain gene. Immunohistochemical studies revealed that the large atypical cells were CD30 (+), CD15 (weakly +), CD20 (-), CD45 (-), Pax5 (weakly +), BOB.1 (-), and Oct2 (-), indicating the coexistence of SMZL with cHL. After the chemotherapy, the patient achieved a clinical/radiologic remission, whereas cHL was detected in liver and bone marrow subsequently. The case indicates that both components of lymphoma can present concurrently as a composite form of lymphoma and both need to be treated adequately.
 ...
PMID:Classical Hodgkin lymphoma concurrently evolving in a patient with marginal zone B-cell lymphoma of the spleen. 1848 99

Seminomas are the most frequent testicular tumors and in spite of specific markers some histological subtypes can be diagnostically challenging due to the potential overlap of morphologic features and a variant antigen expression. Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase present in hematogones, thymic T cells, lymphoblastic lymphoma/leukemia (LBL), and in some cases of acute myeloid leukemia but so far has not been described to be expressed in seminomas. After observing a reactivity of TdT in one case of seminoma, we analyzed ten additional tumors by immunohistochemistry to determine their spectrum of reactivity for TdT. In all seminoma cases investigated (10/10) as well as in two tumor-associated germ cell neoplasias in situ (2/2) the TdT staining intensity was variable but was often moderate to strong and restricted to the nucleus. We conclude that TdT expression in seminomas could represent a diagnostic pitfall in the differential diagnosis of LBL, particularly because both may lack CD45 and/or CD20 expression and-concerning relapse in long-term survivors of testicular cancer-LBL is the most frequent secondary neoplasm in the patients.
 ...
PMID:Expression of terminal deoxynucleotidyl transferase (TdT) in classical seminoma: a potential diagnostic pitfall. 2945 18