Gastrointestinal Hematopathology

Authors

Brice L. Hunt, MD and Zhikai Chi, MD, PhD (Housestaff), Qin Huang, MD, PhD (Faculty)

Subject: Gastrointestinal/Hematopathology
Clinical History

A 49 year old male with a history of human immunodeficiency virus (HIV) presented to the emergency department with abdominal pain, fevers, chills, sweats and fatigue with dyspnea on exertion of one month duration. On review of systems he reported an unintentional 20lb weight loss over this time as well.

Laboratory testing revealed a hemoglobin value of 5.4 g/dL and a positive fecal occult blood test. Computed tomography (CT imaging) detected marked wall thickening of the left colon, suggestive of severe colitis. Colonoscopy showed innumerous polyps throughout the colon ranging in size from 0.2 to 3.0 cm. Multiple biopsies were obtained.

Figures
Biopsy from a colonic polyp

Figure 1: (H&E, 10x). Biopsy from a colonic polyp shows the lamina propria is packed with sheets of mononuclear cells.

Figure 2: (H&E, 40x). The tumor cells are large atypical lymphoid cells with large round to irregular nuclei, prominent nucleoli, a moderate amount of pink cytoplasm and brisk mitotic activity.

classic immunophenotypic profile

Figure 3: A select panel demonstrating the classic immunophenotypic profile for primary effusion lymphoma. The tumor cells express HHV8, CD30 and MUM1. They are negative for B-cell markers CD20 and CD79a as well as plasmacytic marker CD138.

Diagnosis

HHV8 associated extracavitary primary effusion lymphoma

Discussion

Primary effusion lymphoma (PEL) is a rare subtype of large B-cell lymphoma representing approximately 4% of all immunodeficiency syndrome (AIDS)-related lymphomas. It occurs in two forms; classic and extracavitary/solid. PEL classically presents as a lymphomatous effusion in the pleural, pericardial, or peritoneal cavities, but may also manifest as extracavitary masses involving the gastrointestinal tract, lungs, skin and central nervous system. PEL is universally associated with the human herpesvirus 8 (HHV8) and most often occurs in the setting of immunodeficiency. Additionally tumor cells often show coinfection with Epstein-Barr Virus (EBV).

The tumor cells show morphologic variability which ranges from immunoblastic/plasmablastic to anaplastic. The nuclei are large and round to more irregular or lobated with prominent nucleoli. On histological sections these cells may appear more uniform and monotonous than on cytologic specimens. Immunophenotypically the lymphoma cells usually express CD45, but lack other pan B-cell markers (CD19, CD20, CD79a as well as surface and cytoplasmic immunoglobulins). Alternatively, the extracavitary variant may have lower expression of CD45 but higher expression of CD20, CD79a as well as aberrant expression of T-cell markers. Nuclear positivity for HHV8 is a hallmark of PEL.

Due to the morphologic variability of PEL there are several differentials to consider including Burkitt lymphoma, plasmablastic lymphoma, pyothorax-associated lymphoma and HHV8 negative effusion-based lymphoma as well as other large B-cell lymphomas.

Attempts to treat PEL with chemotherapy, highly active antiretroviral therapy and bortezomib have had minimal success as the overall prognosis for patients with PEL is extremely unfavorable. The median survival is <6 months and most patients succumb to disease progression, opportunistic infections and other HIV related complications with one year presentation.

References

1. Cesarman E, Chang Y, Moore PS, Said JW, Knowles DM. Kaposi's sarcoma-associated herpesvirus-like DNA sequences in AIDS-related body-cavity-based lymphomas. N Engl J Med. 1995;332:1186–1191.
2. Kim Y, Park CJ, Roh J, Huh J. Current Concepts in Primary Effusion Lymphoma and Other Effusion-Based Lymphomas. Korean Journal of Pathology. 2014;48(2):81-90. doi:10.4132/KoreanJPathol.2014.48.2.81.
3. Swerdlow SH, Campo E, Harris NL, Jaffee ES, Pileri SA, Stein H, Thiele J (Eds): WHO classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition) IARC: Lyon 2017

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