Differentials
Mantle cell lymphoma
SIGNS / SYMPTOMS
Clinically indistinguishable.
Chronic lymphocytic leukaemia/small lymphocytic lymphoma
SIGNS / SYMPTOMS
Typical clinical features include painless lymphadenopathy, with or without B symptoms. Gastrointestinal disease is uncommon.
INVESTIGATIONS
Immunohistochemistry shows CD5, LEF1, and CD23 positivity; cytogenetic testing often shows del(13q) or trisomy 12; bone marrow biopsy usually shows bone marrow involvement.[23]
Follicular lymphoma
SIGNS / SYMPTOMS
Almost always presents with nodal disease. Extranodal disease is uncommon.
Most patients have widespread disease at presentation, enlarged lymph nodes (typically Waldeyer's ring and cervical lymph nodes), and splenomegaly.[23] Occasionally can present with palpable masses in the abdomen and abdominal pain or GI bleeding.
INVESTIGATIONS
Immunohistochemistry shows CD10 and BCL6 positivity in tumour cells within and between follicles; bone marrow biopsy usually demonstrates bone marrow involvement.[23]
Diffuse large B-cell lymphoma
SIGNS / SYMPTOMS
Symptoms are aggressive, with abdominal pain, vomiting, and haematemesis occurring more commonly than with gastric MALT lymphoma.
INVESTIGATIONS
Biopsy shows medium- to large-sized tumour cells; proliferative index (e.g., Ki-67) is high.
Peptic ulcer disease
SIGNS / SYMPTOMS
Clinically indistinguishable from gastric MALT lymphoma.
INVESTIGATIONS
Molecular testing for immunoglobulin gene rearrangement may help distinguish malignant (clonal) lymphoma from benign (polyclonal) conditions (e.g., hyperplasia, chronic inflammation). In some cases monoclonality can be demonstrated in uncomplicated chronic gastritis, and this may precede the emergence of gastric MALT lymphoma.[39][40]
Chromosomal translocations and histopathological examination of the stomach can differentiate MALT lymphoma from peptic ulcer disease.
Hashimoto's thyroiditis
SIGNS / SYMPTOMS
Causes hypothyroidism that is usually insidious in onset, with signs and symptoms slowly progressing over months to years.
Some of the common symptoms of hypothyroidism include cold intolerance, voice hoarsenesss, painless goiter, pressure symptoms in the neck from thyroid enlargement, slowed movement and loss of energy, menstrual irregularities (typically menorrhagia, infertility, and loss of libido), depression, dementia, and other psychiatric disturbances, as well as memory loss.
INVESTIGATIONS
Elevated TSH with low free T4 levels; antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) antibodies are positive in the majority of cases.
Lymphoepithelial sialadenitis
SIGNS / SYMPTOMS
Clinically indistinguishable from salivary/parotid gland MALT lymphoma.
INVESTIGATIONS
Biopsy of the salivary glands shows a spectrum of histopathological features including: 1) fully benign lymphoid infiltrate, with or without an associated lymphoid follicular structure, without immunoglobulin (Ig) light chain restriction in B cells, and without any features of aggressive behaviour; 2) lymphoproliferative lesions, with or without areas of Ig light chain restriction in B-cells, with the usual presence of centrocyte-like cells. A more or less pronounced lymphoepithelial aggressiveness may be present without definite evidence of malignancy.
B-cell clones are detected in over 50% of cases by molecular genetic methods but this does not correlate with morphological or clinical evidence of overt lymphoma.
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