Haematology - Barbara J. Bain

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affinity for the gastrointestinal tract but this may not necessarily be symptomatic. A subset of patients, as in the case presented here, show a leukaemic presentation with splenomegaly but without lymphadenopathy. Leukaemic non‐nodal mantle cell lymphoma is biologically different and paradoxically, despite the leukaemic manifestation, usually has a more indolent course and an appreciably better prognosis (Nadeu et al. 2020). More aggressive forms of the disease can show mutations in TP53, MYC and CDKN2A. The latter is an important tumour suppressor gene encoding proteins which in turn inhibit MDM2 (a physiological inhibitor of the TP53 pathway). Loss or mutation of either CDKN2A or TP53 leads to chemotherapy resistance and MYC mutation is typically associated with proliferative disease. Note the CD5 negativity here; approximately 5% of mantle cell lymphomas are CD5 negative so morphological assessment alongside genetic and immunohistochemical studies are still required in achieving the correct diagnosis.

      1 Nadeu F, Martin‐Garcia D, Clot G, Díaz‐Navarro A, Duran‐Ferrer M, Navarro A et al. (2020) Genomic and epigenomic insights into the origin, pathogenesis, and clinical behavior of mantle cell lymphoma subtypes. Blood, 136, 1419–1432.

      1 Mantle cell lymphoma:Can result from translocations involving CCND1, CCND2 or CCND3Is derived from marginal zone lymphocytesIs the most common pathology underlying multiple lymphomatous polyposisMay show SOX11 expression on immunohistochemistryUsually expresses CD200For answers and discussion, see page 206.

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      A 6‐month‐old boy, born to consanguineous parents, presented with failure to thrive, developmental delay and pancytopenia. He was found to have significant hearing impairment. His full blood count showed Hb 80 g/l, WBC 2 × 109/l, neutrophils 0.8 × 109/l and platelets 50 × 109/l. The blood film was leucoerythroblastic but abnormal cells were not identified. The bone marrow aspirate was markedly hypocellular. The bone marrow trephine biopsy sections were highly abnormal, showing prominent disorganised trabecular structure and whorls with a significant encroachment on, and reduction in activity of, normal haemopoietic marrow (top images ×10 objective, bottom images ×50). The normal haemopoietic marrow space appears overrun by abnormal disorganised marrow trabeculae. The clinical presentation and marrow findings are indicative of inherited infantile osteopetrosis.

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      1 Infantile osteopetrosis can be associated with:Autosomal recessive or dominant inheritanceDecreased osteoclastsFragile bonesResponsiveness to vitamin D that renders transplantation unnecessaryIncreased osteoclastsFor answers and discussion, see page 206.

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      1 1 Images courtesy of Professor Rob Wynn and Cambridge University Press.

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      A 79‐year‐old man with a 60‐year smoking history presented with the recent onset of anorexia and weight loss with rapidly appearing skin nodules. He had no new respiratory symptoms though he had a longstanding cough attributed to chronic obstructive pulmonary disease. His full blood count showed Hb 133 g/l, WBC 58 × 109/l, eosinophils 35 × 109/l and platelets 500 × 109/l. The blood film confirmed a marked eosinophilia with a number of abnormalities of eosinophil morphology. Hypogranular eosinophils are prominent (all images ×100 objective) with some cells showing 50% loss of cytoplasmic granules (top left). There is also eosinophil cytoplasmic vacuolation (bottom left) and some basophilic granulation (top centre and bottom right). Finally, there are cells with nuclear abnormalities with some showing separation of nuclear components (top right) and even a ring nucleus (bottom centre). It might be assumed that such dramatic morphological abnormalities indicate a primary haematological disorder but this is not the case. A CT scan of chest, abdomen and pelvis showed a solid pulmonary lesion with irregular margins, mediastinal lymphadenopathy and bilateral adrenal masses. A skin biopsy showed a poorly differentiated carcinoma of possible primary lung origin.

      1 Goasguen JE, Bennett JM, Bain BJ, Brunning R, Zini G, Vallespi M‐T et al.; International Working Group on Morphology of MDS (2020) The role of eosinophil morphology in distinguishing between reactive eosinophilia and eosinophilia as a feature of a myeloid neoplasm. Br J Haematol, 191, 497–504.

      2 Leach M (2020) The diagnostic utility of eosinophil morphology. Br J Haematol, 191, 325.

      1 Reactive eosinophilia can occur in:Acute lymphoblastic leukaemiaAcute myeloid leukaemia associated with inv(16)BabesiosisFilariasisStrongyloidiasisFor answers and discussion, see page 206.

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      A 30‐year‐old woman, born in the Philippines, presented at the booking clinic with a pregnancy of 12 weeks’ duration. She gave no prior history of anaemia or blood disorder. Her full blood count showed Hb 130 g/l, WBC 9 × 109/l and platelets 247 × 109/l. The blood film showed prominent ovalocytes, many of which were also macrocytic and stomatocytic. Notably, there were double, transverse and longitudinal stomas (left images ×100 objective) and some cells had Y‐shaped stomas (bottom left). The morphological

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