Primary anaplastic large cell lymphomas of the pancreas.

Primary pancreatic lymphoma is a rare entity. Primary pancreatic anaplastic large cell lymphoma (ALCL), representing a unique type of primary pancreatic lymphoma, is an extremely rare condition. ALCL is a type of T-cell lymphoma that can be divided into two subtypes based on anaplastic lymphoma kinase (ALK) expression: ALCLALK positive, and ALCL-ALK negative.

An unusual myeloid sarcoma.

Myeloid sarcoma is a tumor mass of immature myeloid or monocytic cells (rarely erythroid or megakaryocytic) occurring in an extramedullary site. A de novo promyelocytic granulocytic sarcoma is a very rare tumor. We report a case of a young man presenting with a paraspinal myeloid sarcoma of promyelocytic origin.

Intrasinusoidal Hodgkin Lymphoma; A Mimic of Anaplastic Large Cell Lymphoma.

The distinction between classical Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL) is not problematic in most instances. In rare situations, HL may present with a sinusoidal infiltrative pattern that may mimic ALCL. It is important to use a battery of immunohistochemical stains to differentiate between these two entities as therapy and clinical behavior are different.

Coexisting sarcoidosis and occult mantle cell lymphoma.

Sarcoidosis and lymphoma are two separate entities that need to be considered in the differential diagnosis of lymphadenopathy. Rarely these two diseases may coexist, in which case there may arise a diagnostic challenge, especially when the available sample is limited. We report a case of occult mantle cell lymphoma arising in an individual with a long history of sarcoidosis.

Importance of distinguishing the promonocyte in leukemia.

On rare occasions, a promonocyte may be difficult to morphologically distinguish from a promyelocyte, giving rise to the diagnosis of acute promyelocytic leukemia, particularly the microgranular variant. It is necessary to correctly diagnose these two types of leukemia, as treatment is different for each. Flow cytometry and cytogenetic/molecular studies are useful in distinguishing the two when morphology alone is equivocal.

Mycobacterial spindle cell pseudotumor in a woman with HIV.

Mycobacterial spindle cell pseudotumor (MSP) is a rare benign entity characterized by tumor-like proliferations of spindle-shaped histiocytes containing acid-fast positive mycobacteria. MSPs tend to occur predominantly in immunocompromised individuals and are concerning for a malignant neoplasm. We report a case of MSP occurring in a woman with human immunodeficiency virus and a tumor-like mass in the abdomen.

An unexpected peripheral blood finding: microfilaria.

Microfilaria are not parasites native to the continental United States. On a routine peripheral blood smear examination from an emergency room patient, a microfilaria was identified. The patient was a native African currently living in Texas.

Extramedullary hematopoiesis masquerading as a cranial (clivus) tumor.

Extramedullary hematopoiesis (EMH) is a well-known phenomenon occurring during fetal development. In the postfetal condition, EMH is commonly associated with hematologic conditions including chronic myeloproliferative or lymphoproliferative disorders, leukemias, and chronic and inherited anemias. We report an unusual location for EMH that masqueraded as a cranial tumor.

An unusual presentation of an uncommon lymphoma, hepatosplenic T-cell lymphoma.

Hepatosplenic T-cell lymphoma (HSTCL) is a rare T-cell lymphoma, primarily characterized by extranodal distribution of the malignant cells with intrasinusoidal infiltration of the liver, spleen, and bone marrow, which is associated with a poor outcome. We describe a unique case of a 47-year-old woman with a clinical presentation of headaches, fevers, elevated liver function tests, and hepatosplenomegaly. A liver biopsy revealed a striking hepatic intrasinusoidal infiltrate of lymphocytes.

Simultaneous presentation of two distinct plasma cell neoplasms.

Plasma cell neoplasms consist of a spectrum of diseases characterized by monoclonal proliferations of plasma cells. We report the simultaneous presentation of two distinct plasma cell neoplasms, a very uncommon situation.

Mixed phenotypic acute leukemia.

Mixed phenotypic acute leukemias (MPALs) are a heterogeneous group of rare leukemias constituting about 1% to 5% of all leukemias. MPAL is defined as an acute leukemia that demonstrates expression of a combination of antigens of different lineages so that it is not possible to assign a single lineage to that leukemia. These leukemias have been characterized by relative therapeutic resistance.

Chronic neutrophilic leukemia.

Chronic neutrophilic leukemia is a rare myeloproliferative disorder characterized by a sustained peripheral blood neutrophilia, absence of the BCR/ABL oncoprotein, bone marrow hypercellularity with less than 5% myeloblasts and normal neutrophil maturation, and no dysplasia. This leukemia has been associated with mutations in the colony-stimulating factor 3 receptor that may activate this receptor, leading to the proliferation of neutrophils that are the hallmark of chronic neutrophilic leukemia. We present a case of chronic neutrophilic leukemia and discuss the criteria for diagnosis and the significance of mutations found in this leukemia.

Blastic plasmacytoid dendritic cell neoplasm following acquired erythropoietic protoporphyria.

A 56-year-old Texas rancher with a prior diagnosis of acquired erythropoietic protoporphyria secondary to an underlying myelodysplastic disorder developed an uncommon tumor, blastic plasmacytoid dendritic cell neoplasm (BPDCN). During his initial disease, analysis revealed a mutation, which is the most common mutation associated with BPDCN. This article discusses this unusual hematopoietic neoplasm, the possible evolution from erythropoietic protoporphyria, and the underlying myelodysplastic process.

Epstein-Barr virus-positive diffuse large B-cell lymphoma.

While the World Health Organization included Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) as a provisional entity of a lymphoma occurring in older individuals without any known immunodeficiency in 2008, it has since been recognized that this entity may occur in younger individuals. As a result, the 2016 revision has substituted the modifier "elderly" with "not otherwise specified" (NOS). The NOS highlights that there are more specific entities with neoplastic EBV-positive large B cells such as lymphomatoid granulomatosis.

Plasmablastic plasmacytoma of the breast.

Breast plasmacytomas are extremely rare entities that can be seen as primary malignant neoplasms in the absence of bone involvement or as secondary neoplasms from disseminated multiple myeloma. Clinicians should be aware of this entity, as it may mimic benign and malignant lesions in the breast. Microscopically, immature plasmacytomas may mimic other neoplasms, so caution should be made on histological examination to ensure the correct diagnosis and corresponding therapy.

Myeloid sarcoma causing airway obstruction.

Myeloid sarcoma is an extramedullary collection of blasts of the myeloid series that partially or totally effaces the architecture of the tissue in which it is found. These tumors have been described in many sites of the body, but the skin, lymph nodes, gastrointestinal tract, bone, soft tissue, and testes are most common. They can arise in a patient following the diagnosis of acute myeloid leukemia, but they may also be precursors of leukemia and should be considered diagnostic for acute myeloid leukemia.

Plasma cell myeloma with lymphoplasmacytic morphology and cyclin D1 expression, an uncommon variant.

The genetic complexity of multiple myeloma is due in part to the accumulation of mutations, with primary and secondary events. One such secondary event is the development of a gene mutation that may result in overexpression of cyclin D1. The pathway involving cyclin D1 is intricately involved in cell cycle regulation from the G1 to S phase, and alterations may contribute to tumorigenesis.

Acute promyelocytic leukemia after renal transplant and filgrastim treatment for neutropenia.

Prolonged immunosuppression in solid organ transplant recipients has been considered a risk for developing opportunistic infections and malignancies. Acute leukemia is a rare complication. We report a case of acute promyelocytic leukemia (APL) (FAB M3) after cadaveric renal transplant for focal segmental glomerulosclerosis in a 24-year-old woman.

A case of erythropoietic protoporphyria.

A 53-year-old Texas rancher developed a blistering skin rash that was sensitive to exposure to sunlight. He was referred to hematology with a presumptive diagnosis of porphyria. His peripheral blood counts were within normal limits, and a bone marrow examination revealed erythroid dyspoiesis and ringed sideroblasts.

Metastatic thymoma involving the bone marrow.

Although relatively rare, thymomas can be involved in a considerable variety of clinical presentations. Clinicians should be mindful of the breadth of associations with other diseases, including autoimmune disorders and many secondary nonthymic malignancies. For the pathologist, knowledge of the extremely varied histopathologic presentation of thymoma is vital to formulate a proper differential, workup, and diagnosis.

Primary follicular lymphoma of the duodenum.

Follicular lymphoma, a common nodal lymphoma, is rare in the gastrointestinal tract. When seen in this location, duodenal involvement is frequent. Most patients have localized disease, and survival appears to be excellent even without treatment.

Anaplastic large-cell lymphoma in AIDS.

AIDS-related malignancies may alter clinical courses and result in death in critically ill patients. We present a case of a newly diagnosed AIDS patient with Pneumocystis jiroveci pneumonia, Epstein-Barr virus, and cytomegalovirus infections who was found to have widely metastatic kinase-negative anaplastic large-cell lymphoma. This case demonstrates the diversity in the malignant presentation of HIV-infected patients, outside of the more commonly observed non-Hodgkin lymphomas.

A case series of clinically undiagnosed hematopoietic neoplasms discovered at autopsy.

Objectives: In the United States, autopsy rates have diminished to less than 5% during the last half of the 20th century and the beginning of the 21st century for a multitude of reasons. Many believe this results in unrecognized malignancies that could have explained a patient's death.

Methods: We describe six deaths in which hematopoietic neoplasms were identified at autopsy but were not diagnosed clinically.

Hairy cell leukemia presenting with a lytic bone lesion.

Hairy cell leukemia (HCL) is an indolent neoplasm of small mature B lymphoid cells with characteristic morphologic features usually involving the peripheral blood, bone marrow, and spleen. It constitutes approximately 2% of adult leukemias and has a male predominance. Patients usually present with weakness, splenomegaly, and pancytopenia.