both PBL with and without demonstrable MYC rearrangements. It has been suggested that the presence of an IgH/MYC translocation may indicate a tumour with a worse prognosis and therefore cytogenetic screening should be attempted to assist in risk assessment. 1 However, given that the previously reported cases have all arisen in HIV positive individuals with significant immunosuppression it would appear to be difficult to separate the effects of one disease from the other in terms of overall prognosis. PBL is a rare entity and consequently the numbers of individuals available for study are small. Further investigation is required to develop a greater understanding of the molecular basis of this disease and to determine whether this has prognostic or therapeutic significance. K. L. McGlaughlin* A. Bajel{ C. D. Mow* *Melbourne Pathology, Collingwood, and {Department of Clinical Haematology and BMT, The Royal Melbourne Hospital, Grattan Street, Parkville, Victoria, Australia Contact Dr K. L. McGlaughlin. E-mail: karen.mcglaughlin@mps.com.au Acknowledgements: The molecular studies were performed at St Vincent’s Hospital, Melbourne. 1. Bogusz AM, Seegmiller AC, Garcia R, Shang P, Ashfaq R, Chen W. Plasmablastic lymphomas with MYC/IgH rearrangement: report of three cases and review of the literature. Am J Clin Pathol 2009; 132: 597– 605. 2. Chuah KL, Ng SB, Poon L, Yap WM. Plasmablastic lymphoma affecting the lung and bone marrow with CD10 expression and t(8;14)(q24;q32) translocation. Int J Surg Pathol 2009; 17: 163–6. 3. Yotsumoto M, Ichikawa N, Ueno M, Higuchi Y, Asano N, Kobayashi H. CD20-negative CD138-positive leukemic large cell lymphoma with plasmablastic differentiation with an IgH/MYC translocation in an HIV-positive patient. Intern Med 2009; 48: 559–62. 4. Dawson MA, Schwarer AP, McClean C, et al. AIDS-related plasmablastic lymphoma of the oral cavity associated with an IgH/ MYC translocation – treatment with autologous stem-cell transplantation in a patient with severe haemophilia-A. Haematologica 2007; 92: e11–2. 5. Colomo L, Loong F, Rives S, et al. Diffuse large B-cell lymphomas with plasmablastic differentiation represent a heterogeneous groups of disease entities. Am J Surg Pathol 2004; 28: 736–47. 6. Rafaniello Raviele P, Pruneri G, Maiorano E. Plasmablastic lymphoma: a review. Oral Dis 2009; 15: 38–45. 7. Vega F, Chang CC, Medeiros LJ, et al. Plasmablastic lymphomas and plasmablastic plasma cell myelomas have nearly identical immunophenotype profiles. Mod Pathol 2005; 18: 806–15. DOI: 10.3109/00313025.2010.523693 Lymphocyte vacuolation: clue to inherited metabolic disease Sir, Early diagnosis and management of inherited metabolic disorders can prevent or mitigate the associated morbidity and mortality. Acute observation of morphological changes in blood film aids in diagnosis of these conditions. We report a case wherein careful examination of the blood film resulted in diagnosis of an inherited metabolic condition. A 5-month-old girl presented with a 3 day history of sweating, feeding intolerance and a wheeze. Her medical history included admissions for suspected bronchiolitis over the previous 2 months. On clinical evaluation she was tachypnoeic with signs of cardiac failure. There was clinical and radiological evidence of cardiomegaly. Her liver was enlarged, palpable 3 cm below the costal margin and she was noted to be hypotonic. There were no obvious dysmorphic features or history of developmental delay. The full blood examination revealed haemoglobin (Hb) 128 g/L, white cells 11.9 6 10 9 /L, platelets 595 6 10 9 /L and a normal differential count. Blood film revealed presence of well-demarcated small cytoplasmic vacuoles in the lymphocytes raising the possibility of an underlying metabolic disorder (Fig. 1). Cytochemistry revealed granular positivity of lymphocytes on periodic acid-Schiff (PAS) reaction (Fig. 2). Based on these findings further investigations were undertaken to identify an underlying metabolic disorder. The urine organic acid and mucopolysaccharide screen was normal. However, there was marked reduction in acid a glucosidase activity in leukocytes (0.02 mmol/h/L; reference range 0.3–10.0) confirming the diagnosis of Pompe’s disease (type II glycogen storage disorder). Lymphocyte vacuolation occurs in a wide spectrum of inherited metabolic disorders. Cytochemistry may provide a clue to the metabolic product responsible for vacuolation and may point to a specific underlying diagnosis (glycogen gives a positive PAS reaction in Pompe’s disease, cholesterol esters give a positive oil red O reaction in Woolman’s disease). 1 However, the definite diagnosis requires specific enzyme assays. A retrospective review of 2550 blood films from a tertiary institution revealed presence of lymphocyte vacuolation in 156 cases (6.1%). 2 The frequency of vacuolated Fig. 1 Blood film (higher magnification) showing well demarcated small cytoplasmic vacuoles in the lymphocytes. CORRESPONDENCE 699