Pathology Notes

Mycosis fungoides   Updated: 03/17/2021 © Jun Wang, MD, PhD General features Most common type of cutaneous T cell lymphoma More commonly seen in adults/elderly, men, African Unknown etiology Clonal CD4+ T cells Diagnosis based on clinical presentations, biopsy, molecular testing and immunopathologic profiling  Clinical presentations Four stages: Patch, plaque, tumoral and Sézary syndrome Patch stage: Pruritic erythematous macules or patches with telangiectasia and atrophy, may disappear spontaneously Plaque stage: Pruritic thichened plaques , may resemble psoriasis Tumoral stage: Tumor formation , either from plaques or de novo, may ulcerate Sézary syndrome Commonly erythroderma (80% of total body surface), may be scaly Lymphadenopathy Sézary cells in skin, lymph nodes and peripheral blood Usually do not evolve from patches, plaques or tumors May have marrow involvement Key morphological features Patch stage: Psoriasiform changes, but intraepidermal clonal

Adult T Cell leukemia/lymphoma Updated: 0 7/16/2019 © Jun Wang, MD, PhD General features Aggressive Endemic with Human T Cell Leukemia Virus Type I (HTLV-I) Clinical presentations Wide spread lymph node and peripheral blood involvement Key pathogenesis Human T cell leukemia virus Viral protein (Tax) activates NF- k B Key Laboratory findings Hypercalcemia due to increased osteoclastic activity Key morphological features Cloverleaf/flower cells : Neoplastic T cells with agranular basophilic cytoplasm, multilobated nuclei, in the appearance of clover leaf Markers Positive: CD3, CD4 Negative: CD30, ALK Back to lymphoid neoplasms Back to contents

Reactive leukocytosis Updated: 09/26/2020 © Jun Wang, MD, PhD General features Usually a reaction to physiological (stress, exercise) or pathological (inflammation, underlying neoplasm, allergic reactions, hereditary) processes Results of elevated levels of growth factor, cytokines, etc Specific terms Left shift : Increased circulating immature leukocytes, usually neutrophils, caused by releasing of stored leukocytes, associated with bacterial infection Leukemoid reaction : Neutrophils above 50 x 10 3 /mm 3 , more immature cells, particularly myelocytes, associated with severe infection, intoxications, severe hemorrhage, acute hemolysis, etc Leukoerythroblastic reaction : Nucleated red blood cells and immature myelocytes in circulation, associated with severe marrow function disruption, may be seen in myelofibrosis, may mimic myeloid neoplasms . Neutrophilia Usually associated with acute infection, steroid usage, inflammations, metabolic disorders such as ketoac

Splenomegaly Updated: 07/13/2020 © Jun Wang, MD, PhD General features Enlarged spleen >400 g Massive if > 1000 g Various etiology, usually associated with splenic hyperfunction Etiology Part of systemic presentation of inflammation: Such as in subacute bacterial endocarditis or infectious mononucleosis Local inflammation: Sarcoidosis, abscess, etc RBC destruction: Hereditary spherocytosis, thalassemia Congestive: Portal hypertension Ectopic hematopoiesis: Myeloproliferative neoplasm , etc Neoplastic: Lymphomas, metastatic malignancy, etc Clinical presentations Various Key pathogenesis Splenic hyperfunction Key Laboratory findings Nonspecific Anemia, leukopenia, or thrombocytopenia Less mature white cells, nucleated red cells , teardrop-shaped red cells , etc Diagnostic approaches to identify etiology History CBC and peripheral blood morphology Bone marrow biopsy if hematopoietic disorder suspicious Flow cytometry if lymphocyte pre

Hemophagocytic lymphohistiocytosis Updated: 08/04/2020 © Jun Wang, MD, PhD General features Generalized, non-malignant histiocytosis Rare but aggressive and life threatening Excessive activation of immune activity Familial : infants/young children, autosomal recessive Acquired : EBV+ immunocompromised, or associated with other infections or malignancy May develop from Chediak-Higashi syndrome May involve any organ Repeated biopsy of bone marrow, lymph nodes, etc if necessary for diagnosis Clinical presentations Acute febrile illness Splenomegaly and hepatomegaly Lymphadenopathy Skin rash Key pathogenesis Abnormal activation of macrophages Over expression of calreticulin (CRT) Underexpression of CD47 Key Laboratory findings Pancytopenia Key morphological features Hemophagocytosis Indicators for diagnosis Fever with hepatosplenomegaly and cytopenia, as well as elevated ferritin Genetic abnormalities If familial, associated

Hyposplenism Updated: 08/02/2020 © Jun Wang, MD, PhD General features Reduced splenic function Various etiologies Clinical features Increased risk for infection, especially encapsulated bacteria, such as pneumococcus Etiology Splenectomy Infarction, such as seen in sickle cell disease Others including congenital abnormality, celiac disease, etc Key Laboratory findings Howell-Jolly bodies Pappenheimer bodies Target cells Back to benign white cell disorders Back to contents

Chronic lymphadenitis Updated: 07/23/2020 © Jun Wang, MD, PhD General features Chronic inflammation Various etiology Associated with toxoplasmosis, early HIV infection, rheumatoid arthritis, etc Clinical presentations Painless enlargement of lymph node Key morphological features Follicular hyperplasia with normal architecture Prominent post capillary venules Usually numerous tangible body macrophages Diagnostic approaches Special stains Immunohistochemistry Molecular studies Flow cytometry to rule our monoclonal lymphocytic proliferation Back to benign white cell disorders Back to contents