@entity1822 is an uncommon @entity5 . Herein, we describe the clinicopathological features and biological behaviour of these @entity5 , and provide a practical approach to differential diagnosis, particularly with @entity5 ( @entity5 ). We report two cases in elderly @entity1 . In the first, the lesion was 2 cm from the anal sphincter, while it was located in the rectal ampulla in the second case. Histologically, both @entity5 were characterized by pleiomorphic, large spindle cells, presenting numerous mitoses and marked nuclear atypia. Immunohistochemical analysis showed that @entity5 cells coexpressed both actin and @entity2283 , whereas @entity2467 and S100 protein were negative. The final diagnosis was @entity1822 . One of the @entity1 died of pulmonary @entity3 within six months. The second @entity1 had bone @entity3 , but was lost to follow up. This report underlines the potential diagnostic problems raised by @entity1822 and emphasizes the role of immunohistochemistry in achieving correct diagnosis, which has important clinical, therapeutic and prognostic consequences.

XXXX : report on two cases and a practical approach to differential diagnosis.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient', 'men'] @entity2283 :: ('1674', 'Gene') :: ['desmin'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumour', 'tumours', 'gastrointestinal stromal tumours', 'malignancy', 'GIST'] @entity1822 :: ('MESH:D007890', 'Disease') :: ['leiomyosarcoma', 'Rectal leiomyosarcoma', 'rectal leiomyosarcoma'] @entity3 :: ('MESH:D009362', 'Disease') :: ['metastasis'] @entity2467 :: ('3815', 'Gene') :: ['CD117']
@entity1822 :: (MESH:D007890,Disease) :: ['Rectal leiomyosarcoma']
