WBR0781
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Hematology, SubCategory::Oncology |
| Prompt | [[Prompt::A 32 year old man presents to his primary care physician with 1 month of weakness and fatigue. The patient reports that he has also been short of breath with even minor activity. On physical exam, the physician notices several bruises on the patient’s abdomen and lower extremities although the patient denies any trauma. Splenomegaly is also noted 5 cm below the left costal margin. The physician orders a set of labs and a blood smear that are shown below. What other findings do you expect to observe?
Hemoglobin = 6.8 MCV = 78 White Blood Cells = 17230 %Neutrophils = 4% %Lymphocytes = 96% Platelets = 13000
|
| Answer A | AnswerA::Terminal deoxynucleotidyl transferase positivity on immunohistochemistry |
| Answer A Explanation | AnswerAExp::Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase expressed in immature B and T cells and is used in the diagnosis of acute lymphoblastic leukemia specifically pre-B and pre-T subtypes. |
| Answer B | AnswerB::TRAP stain positivity |
| Answer B Explanation | AnswerBExp::TRAP positivity is typical of hairy cell leukemia |
| Answer C | AnswerC::Schistocytes |
| Answer C Explanation | AnswerCExp::Schistocytes are seen in patients with microangiopathic hemolytic anemia like TTP or DIC. |
| Answer D | AnswerD::Bite cells and Heinz bodies |
| Answer D Explanation | AnswerDExp::Both bite cells and heinz cells are seen in patients with hemolytic anemia secondary to G6PD deficiency. |
| Answer E | AnswerE::Peroxidase positivity |
| Answer E Explanation | AnswerEExp::Peroxidase positivity is seen in AML cells due to the presence of Auer rods. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Hairy cell leukemia is a slowly progressive hematologic malignancy classically seen in older males. Patients usually present with anemia, and thrombocytopenia and neutropenia despite normal or elevated white cell count. On physical exam, splenomegaly is common along with ecchymoses secondary to the low platelets. Diagnosis is usually made by peripheral blood as well as bone marrow smear showing characteristic hairy cells (white blood cells with irregular, hair-like margins). Patients are usually at very high risk of infection given their immune status. The origin of hairy cells is B-lymphocytes although they exhibit features of monocytes.
Zinzani PL, Pellegrini C, Stefoni V, et al. Hairy cell leukemia: evaluation of the long-term outcome in 121 patients. Cancer. 2010;116(20):4788-92. |
| Approved | Approved::No |
| Keyword | WBRKeyword::Hairy cell leukemia, WBRKeyword::TRAP |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
