We report here a rare presentation of an extra-nodal non-Hodgkin's lymphoma. Both clinical presentation radiological findings were suggestive of psoas abscess. Surgical debridement was performed and histopathological examination of the tissue sample revealed the diagnosis of non-Hodgkin's lymphoma. It is therefore important to note that non-Hodgkin's lymphoma can mimic psoas abscess and that psoas lesion with vertebral involvement does not necessarily indicate infection. It is always advisable to obtain needle biopsy to establish diagnosis before embarking on surgical intervention. The practice to send any suspicious tissue obtained intra-operatively for histopathological examination is also warranted.