Peripheral blood smear from a patient with suspected chronic lymphocytic leukemia (CLL) shows a predominance of small, mature-appearing lymphocytes with scant cytoplasm and clumped nuclear chromatin, accompanied by fragile cells that readily disrupt during smear preparation, producing numerous smudge or basket cells visible on the slide. The image depicts a single smudge cell in the upper right, with numerous small darkly staining lymphocytes occupying the field. The smear was prepared with Wright-Giemsa stain and examined under light microscopy at high magnification (approximately 1000x total magnification with oil immersion). Clinically, CLL is defined by absolute mature lymphocytosis of ≥5.0 × 10^9/L sustained for ≥3 months, often asymptomatic and detected incidentally on complete blood count. Morphology alone is insufficient for diagnosis; immunophenotyping showing co-expression of CD5, CD19, CD23 with weak surface immunoglobulin and light chain restriction supports CLL diagnosis. Smudge cells result from fragile leukemic cells and reflect underlying cytoskeletal fragility, though they are not specific. The image illustrates typical features: monomorphic lymphocytes, scant cytoplasm, condensed chromatin, and absent prominent nucleoli. This finding has diagnostic significance, guiding further workup, including flow cytometry, cytogenetics, and molecular studies, to distinguish CLL from other chronic lymphoproliferative disorders such as small lymphocytic lymphoma (SLL), mantle cell lymphoma, prolymphocytic leukemia, and reactive lymphocytosis.

This image depicts a peripheral blood smear prepared with Wright-Giemsa stain and examined under light microscopy at high magnification. The predominant features are small, mature-appearing lymphocytes with scant cytoplasm and discrete basophilic nuclei interspersed among erythrocytes. A characteristic subset of circulating lymphocytes displays short, polarity-restricted cytoplasmic villi (finger-like projections) consistent with splenic marginal zone lymphoma (SMZL) involvement of peripheral blood. The villi are typically slender and localized to one pole of the cell, unlike the longer, circumferential villous extensions seen in hairy cell leukemia, which aids in differential diagnosis. Some lymphocytes appear slightly irregular or irregular nuclear contours; occasional larger atypical cells may be present but are less common. The background shows normocytic red cells with normal distribution; platelets are not prominent. This cytomorphology supports SMZL in the context of known splenomegaly or lymphoproliferative disease and is often corroborated by immunophenotyping and molecular studies. Clinically, peripheral blood involvement occurs in roughly half to two-thirds of SMZL cases and helps establish disease burden. The image illustrates the diagnostic utility of meticulous peripheral smear review for small-vessel lymphocytosis and villous lymphocytes, informing differential diagnoses, guiding flow cytometry panels, and contributing to monitoring and prognosis.

Peripheral blood smear prepared from a patient with suspected plasma cell leukemia (PCL) was examined by bright‑field light microscopy after Wright‑Giemsa staining. The smear shows several circulating plasma‑cell–like elements, including four conspicuous proplasmacytes with dispersed nuclear chromatin and prominent nucleoli, as indicated by arrows in the original figure. In addition, background erythrocytes exhibit rouleaux formation, a common feature in paraproteinemic states. The cells display eccentrically placed nuclei with pronounced basophilic cytoplasm and a coarse chromatin pattern; occasional cells show a perinuclear clearing (Golgi rim) suggestive of plasmacytic differentiation. Immunoglobulin light‑chain restriction is not determined on this smear alone but flow cytometry or immunohistochemistry would typically confirm clonal plasma cells. Relative proportions indicate that neoplastic plasma cells constitute a substantial fraction of leukocytes, consistent with plasma cell leukemia rather than reactive plasmacytosis. PCL is an aggressive myelomatous process often presenting with cytopenias, organomegaly, and sometimes lymphadenopathy; prognosis is poor, and treatment responsiveness is limited. This image illustrates characteristic morphologic features used for differential diagnosis against multiple myeloma, Waldenström macroglobulinemia, and other causes of plasmacytosis. Clinically relevant keywords include plasma cells, rouleaux, Wright‑Giemsa stain, 100X oil, peripheral blood, leukemia, myeloma, and hematologic malignancy.

Histopathology; Hematoxylin and Eosin stained gallbladder tissue demonstrating pure eosinophilic infiltrate within the lamina propria. The mucosal architecture is preserved without stromal necrosis or significant neutrophilic infiltration. Eosinophils appear as round to irregular cells with bilobed or multilobed nuclei and abundant bright pink-orange cytoplasmic granules, forming dense networks in the lamina propria surrounding ductal structures and capillaries. The submucosa is largely unremarkable, and no mural granulomas or ulceration are evident. Vascular congestion may be present secondary to inflammatory edema. Scattered lymphocytes and plasma cells are minimal, with eosinophils constituting the predominant inflammatory cell type. A scattered macrophage population is observed adjacent to small vessels. No gallstones are visible in this field, and there is no evidence of acute neutrophilic cholangitis. This pattern is characteristic of eosinophilic cholecystitis, a rare inflammatory variant often linked to allergic or parasitic processes, drug reactions, or hypereosinophilic syndrome. Clinically, eosinophilic cholecystitis may present with right upper quadrant pain and cholecystitis-like symptoms, but peripheral eosinophilia or serologic allergy markers may be absent. The diagnostic significance lies in recognizing eosinophil-predominant inflammation, guiding differential diagnosis, investigative workup for eosinophilia, and management focusing on underlying triggers and symptomatic gallbladder relief.

Histopathology: Light microscopy of a gastrointestinal mucosal biopsy stained with Hematoxylin and Eosin reveals a dense inflammatory infiltrate within the lamina propria. The predominant cellular population comprises eosinophils, characterized by bilobed or irregular nuclei and abundant bright pink cytoplasmic granules, intermixed with a smaller number of mononuclear lymphocytes. Epithelial architecture within this field shows intact surface epithelium without definite crypt distortion or ulceration; no granulomas or conspicuous vasculitis are evident in the sampled area. The surrounding stroma appears mildly edematous with scattered plasma cells and occasional neutrophils. In this image, the eosinophilic infiltrate is conspicuous and may extend around mucosal glands and vessels. Such a pattern is compatible with eosinophilic gastroenteritis or hypersensitivity reactions and could reflect parasitic infection, drug-induced hypersensitivity, or food allergy, depending on clinical context. Normal variant eosinophil counts in the lamina propria can be elevated in the GI tract; therefore correlation with peripheral eosinophilia and clinical symptoms is essential. Diagnostic significance: the presence of tissue eosinophilia in the lamina propria supports a non-neoplastic inflammatory process; differential diagnoses include eosinophilic colitis/enteritis, inflammatory bowel disease with eosinophilia, or secondary eosinophilia due to parasites. Clinical correlation with symptoms (abdominal pain, diarrhea), stool studies, and serologies is recommended.

A multi-panel figure containing diagnostic imaging, an electrocardiogram (ECG), and a blood smear. Panel A presents axial PET/CT fusion and CT images of the thoracic and upper abdominal regions, showing a soft tissue mass near the esophageal hiatus and retroperitoneal abdominal trunk with hypermetabolic fluorodeoxyglucose (FDG) uptake, indicating tumor recurrence or metastasis. Panel B displays a 12-lead ECG strip demonstrating arrhythmias including premature atrial contractions (PACs) and premature ventricular contractions (PVCs). Green arrows highlight mild ST-segment depression in leads V5 and V6, while the blue arrow points to significant T-wave morphology changes, suggesting immunotherapy-related myocardial injury. Panel C is a peripheral blood smear micrograph showing two neutrophils with a left shift in nuclei (indicated by blue arrows), characterized by immature band forms, which is suggestive of an acute inflammatory response or infection. This composite illustrates the clinical monitoring of a patient with esophageal squamous cell carcinoma experiencing immune-related adverse events.

This hematology infographic illustrates the metabolic reprogramming of neutrophils during homeostasis. The top panel depicts neutrophil development (granulopoiesis) from hematopoietic stem cells (HSCs) through various stages: Myeloblast (MB), Promyelocyte (PM), Myelocyte (MC), Metamyelocyte (MM), Band cell (BC), and segmented Neutrophil (SN). Morphological changes show nuclear progression from round/ovoid to indented and ultimately multi-lobed. The bottom panel highlights a significant immunometabolic shift. Immature stages (HSCs to Metamyelocytes) are predominantly reliant on mitochondrial respiration, utilizing fatty acids and glucose to fuel the TCA cycle and oxidative phosphorylation (OXPHOS) for ATP generation; this metabolic state sustains early cellular differentiation. In contrast, mature neutrophils (Band cells and SNs) transition to being predominantly reliant on glycolysis. In these mature cells, glucose and glycogen fuel the pentose phosphate pathway and glycolysis to produce ATP, which sustains effector functions including chemotaxis, ROS production, apoptosis, and NET formation. The diagram emphasizes the shift from high mitochondrial activity in progenitors to glycolytic dominance in terminally differentiated innate immune cells.