Squash cytology of primary central nervous system lymphoma in an immunocompetent patient
This was a case report of a 38-year-old male patient who was admitted to neurosurgery with a history of headache and neck pain since 2 months. No history of antecedent head trauma, febrile illness, photophobia, seizures or previous diagnosis of any malignancy was present. He didn′t have lymphadenopathy or hepatosplenomegaly. Neurologic examination was not revelatory as no abnormality was found. His peripheral smear examination was normal. He was negative for human immunodeficiency virus (HIV).\nMRI of the brain revealed a well-defined lobulated focal mass measuring 4.5 cm × 3.6 cm × 3.5 cm with extensive adjacent white matter edema in right parieto-occipital lobe causing mass effect on right lateral and third ventricle and basal ganglia region with contralateral midline shift of 9 mm. On T1-weighted images mass was isointense to gray matter []. On T2-weighted and fluid-attenuated inversion recovery images, it appeared iso to mildly hyperintense []. There was mild restricted diffusion. The lesion showed intense homogeneous enhancement on post contrast study [Figure and ]. Small area of central necrosis was seen within the mass. MR spectroscopy revealed an elevated choline and lipid lactate. MRI findings were concluded as glioma.\nPatient underwent craniotomy for micro-neurosurgical complete resection by aspiration of the suspected glioma. Squash preparations were made from tissue received for frozen section and stained with hematoxylin and eosin. Monomorphic lymphoid tumor cells were seen without any fibrillary background []. The cells had large nuclei with prominent nucleoli and scant to moderate cytoplasm. Further, lymphoid cells having a blast like appearance with cytoplasmic vacuoles were recognized better on Leishman stain []. Tingible body macrophages and lymphoglandular bodies were seen. The frozen sections showed the tumor cells in sheets, but the cytologic details were not clear.\nWith intraoperative diagnosis of lymphoma infiltration on squash smears, on table bone marrow aspiration was done from the sternum to rule out hemopoietic malignancy in the marrow. The bone marrow smears showed normal marrow cells.\nA squash unstained smear was further studied with immunocytochemistry for CD45 (with a satisfactory positive control). The smears showed cytoplasmic CD45 positivity in intact tumor cells [].\nThe paraffin sections revealed the typical lymphoma cells displaying perivascular pattern and invading the brain [Figure and ]. The starry sky appearance was also seen []. The diagnosis of PCNSL was conferred. The immunohistochemical studies showed CD20 positivity [] in lymphoma cells while they were negative for CD3, CD10, Bcl2, Bcl6 [Figure –] and CD99. CD3 positive reactive T cells were seen amidst the lymphoma cells []. The negativity of lymphoma cells for CD10, Bcl2, Bcl6 and positivity to CD20 indicate the non-germinal center B-cell phenotype.\nThe final diagnosis of diffuse large B cell primary CNS lymphoma (DLBCL) was given. Post-operative contrast CT showed complete removal of the lesion and the patient received chemo and radiotherapy. MRI after 2½ years follow-up showed no evidence of recurrence.