Bone marrow-restricted aberrant myeloperoxidase expression in B-acute lymphoblastic leukemia: A diagnostic dilemma and mimicry of mixed phenotype acute leukemia.

Myeloperoxidase (MPO) is the most specific marker of the myeloid lineage, essential for diagnosing acute myeloid leukemia and mixed phenotype acute leukemia with myeloid components. In this regard, we present a unique case of B-acute lymphoblastic leukemia (B-ALL) with isolated MPO expression in bone marrow blasts detected by flow cytometry and immunohistochemistry, while peripheral blood blasts were negative for MPO expression. In this report, our discussion encompasses diagnostic pitfalls from a laboratory testing perspective in similar cases and includes a literature review. Furthermore, we emphasize the necessity of conducting a comprehensive analysis for the accurate diagnosis of MPO-positive B-ALL cases.

A Rare Autopsy Case of Aggressive Combined Hepatocellular-Cholangiocarcinoma in 59-Year-Old Female.

Combined hepatocellular-cholangiocarcinoma (cHCC-CC) is a liver tumor with features of both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). It consists of intermingled malignant biliary and hepatic tissue and thus a distinct entity, rather than two separate coexisting malignancies. A 59-year-old female with a history of hepatitis C and cirrhosis presented with abdominal pain and altered mental status. She developed hematemesis, and despite extensive interventions, she expired one day after her initial presentation. At autopsy, the liver was diffusely and markedly fibrotic with numerous nodules of varying size with invasion into adjacent vasculature. Microscopic examination of the nodules revealed cHCC-CC with stem cell features, lymphovascular invasion, and tumor emboli scattered throughout the right lung. The patient had end-stage liver disease due to the accumulation of damage and consequent fibrosis. This led to portal hypertension with subsequent massive gastrointestinal bleeding, hemorrhagic shock, and death. cHCC-CC is a rare, aggressive primary liver tumor with a poor prognosis. It can present with a cirrhotomemetic pattern with small nodules that can evade clinical and radiographic detection. Autopsy findings can provide valuable insights into the pathogenesis and clinical course of cHCC-CC, highlight the aggressive nature of the disease, and may inform future diagnostic and therapeutic strategies. Accurate diagnosis of this tumor is important for patient management and prognostication.