Clinical context

A patient presents unwell

At a glance

Stain	MGG

About Large Granular Lymphocytic Leukaemia (LGLL)

Large granular lymphocytic leukemia (LGLL) is a rare, slow-growing blood cancer. It happens when abnormal cytotoxic T cells or natural killer (NK) cells multiply and live too long. Most cases are chronic and diagnosed in people over 60, frequently linked to autoimmune issues like Rheumatoid Arthritis.

T-LGLL makes up about 85% to 95% of cases with the remainder being NK cell. Morphologically these two are identical. The key finding is the presence of large granular lymphocytes in the peripheral blood - they really aren't normally visible in healthy individuals. There will often be associated neutropenia.

The vast majority of cases - more than 90% are chronic, slow growing and the main problem is that they can trigger immune cytopenias, particularly neutropenia.

Treatment is with chemotherapy.

Morphological features

Large Granular lymphocytes

LGL's can be tricky. They have some features or monocytes (small vacuoles, copious cytoplasm) but they don't have the nuclear involution we see in monocytes. They have granules, which we wouldn't normally see in lymphocytes. They could be mistaken for myeloid precursors, but the nuclear chromatin is all wrong for an immature cell. Watch out for these. These are LGLs.

Large Granular Lymphocyte

This cell has a nucleus and cytoplasm which in colour matches a lymphocyte, but has granules and too much cytoplasm to be a normal lymphocyte. It is an LGL. .

Neutrophil

This cell is noteworthy here because it's quite lonely! There aren't very many neutrophils in the film. The patient is quite neuropenic as a consequence of the LGL, and neutropenia is one of the main indications for treatment in LGLL. Absolutely worth noting the absence (or presence) or neutrophils in a patient film with LGLL.

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