Primary anaplastic large cell lymphoma arising from central nervous system.

A 22-year-old man presented at the emergency department with progressive headache, vomiting and horizontal diplopia over 2-month period. He also developed blurred vision in his left eye. He complained of loss of appetite for the past 2 months, resulting in a 5-kg weight loss. Examination upon arrival revealed papilledema and bilateral abducens nerve palsy. Motor and sensory functions were intact. Magnetic resonance imaging (MRI) of the brain revealed multiple extra-axial nodular enhancing lesions with size of 5-10 mm mainly along with both sides of falx cerebri and vasogenic brain oedema (Fig. 1). Stereotactic brain biopsy was performed to obtain tissue diagnosis. Histologic examination revealed brain infiltration by few atypical cells hidden amongst abundant and mixed population of inflammatory cells including lymphocytes and histiocytes. The atypical cells are large cells with horseshoe nuclei (red arrow; Fig. 2A ×100 and Fig. 2B ×400). Immunohistochemistry showed strong, uniform CD30 expression (Fig. 2C ×400) and cytoplasmic ALK staining (Fig. 2D ×400), as well as for CD3 (Fig. 2E ×400) and CD68 (Fig. 2F ×400). B-cell markers (CD20) were negative (Fig. 2G ×400).