Page 355 - Concise Pathology for Exam Preparation ( PDFDrive )

340 SECTION II Diseases of Organ Systems

(f) The North American type preferentially involves the abdomen (bowel, retroperito-
neum and ovaries).
(g) Tumour cells are uniform with round to oval nuclei (approximately, the size of
nuclei of macrophages), 2–5 nucleoli and moderate amount of basophilic or
amphophilic cytoplasm.
(h) Neoplasm characterized by a high mitotic rate and cell death leading to the pres-
ence of numerous macrophages with debris. These macrophages are often
surrounded by a clear space creating a characteristic ‘starry sky’ appearance.
(i) Tumour cells express surface IgM, kappa and lambda light chains and pan B-cell
markers (CD19, CD20 and CD10).
(j) Chromosome analysis may show 8; 14 or 2; 8 or 8; 22 translocations. Most trans-
locations fuse MYC with IgH gene on chromosome 14 resulting in dysregulation
and overexpression of MYC protein.
(k) Antibodies to EB viral capsid antigen may be present.
6. Mucosa-associated lymphoid tissue (MALT) lymphoma (extranodal marginal zone
lymphoma)
(a) Low-grade mature B-cell tumour that arises from mucosa-associated lymphoid
tissue (MALT).
(b) Seen in salivary glands, stomach, small and large bowel, lungs, orbit and breast.
(c) Gastric type of MALT lymphoma is associated with Helicobacter pylori infection.
Salivary gland MALT is associated with Sjögren syndrome indicating sustained
antigenic stimulation may contribute to development of these lymphomas.
(d) It is mainly seen in elderly patients with median age of 60 years.
(e) MALT lymphomas may remain localized to the organ from which they arise or may
spread to the surrounding lymph nodes.
(f) Bone marrow involvement is uncommon and occurs in only 15% cases. Distant
metastasis is possible.
(g) Prognosis is good in most cases (5-year survival of 75%).

Common Mature Peripheral T-Cell Malignancies
1. Mycosis fungoides and Sézary syndrome
(a) Cutaneous T-cell lymphomas composed of neoplastic CD41 T cells that home to
the skin.
(b) The patient presents with chronic erythrodermic rash manifesting as a localized
plaque-like lesion (plaque phase) which later becomes nodular and ulcerated
(tumour phase).
(c) Histological findings include infiltration of the epidermis and upper dermis by
neoplastic T cells, which have a cerebriform nucleus characterized by marked
infolding of the nuclear membrane.
(d) In some cases, a leukaemic phase called Sézary syndrome appears, which is
characterized by:
(i) Generalized exfoliative erythroderma
(ii) Tumour cells in the peripheral blood
(e) Patients with erythrodermic phase of mycosis fungoides usually survive for many
years; survival less (1–3 years) for patients in tumour phase of the disease, visceral
disease and Sézary syndrome.
2. Adult T-cell lymphoma/leukaemia
(a) Caused by a retrovirus, human T-cell lymphotropic virus-I (HTLV-I)
(b) Patients are infected through transplacental transmission, blood transfusion or
sexual contact.
(c) Most patients have an aggressive disease characterized by lymphadenopathy,
hepatosplenomegaly, skin infiltration, hypocalcaemia and lytic bone lesions.
(d) Peripheral smear usually reveals characteristic, pleomorphic abnormal CD4-positive
cells with indented nuclei.
(e) Leukaemic cells express high levels of CD25 (The IL2 receptor a chain).
(f) Extremely aggressive disease with a median survival of 8 months. A few patients
have long, chronic course.
(g) Combination chemotherapy may prolong life but does not produce remissions.

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