XXXX . A clinicopathologic study and review of the literature.

@entity1 @entity3883 @entity788 @entity353 @entity5 @entity3017 @entity158 @entity3
@entity3017 is a rare @entity788 with a distinctive histologic appearance that generally affects @entity1 and young @entity1 . We have studied 14 cases of @entity3017 and reviewed 41 previously reported examples. Nine of our cases occurred in @entity1 (from newborn to 4 years old; mean, 2.4), and five affected adults (from 19 to 56 years old; mean, 40). There were 8 male cases and 6 female cases. Most @entity1 presented with incidental abdominal masses, although @entity158 , @entity353 , and @entity3883 were present, but rarely. The @entity5 were very cellular microscopically, with cytologically uniform epithelial cells arranged in sheets and nests. Well-formed acinar structures were a consistent feature, and several cases contained ectatic ductular formations, rarely exhibiting intracellular mucin. Consistently present were squamoid corpuscles: circumscribed, whorled nests of plump spindle cells with a squamous appearance and occasional keratinization. The stroma was moderate to abundant and frequently quite cellular (especially in the pediatric cases). By immunohistochemistry, the @entity5 exhibited acinar, endocrine, and ductal differentiation, with positivity for pancreatic enzymes (100%), endocrine markers (82%), and carcinoembryonic antigen (85%). Ultrastructural examination most commonly revealed acinar differentiation, although mucigen granules and neurosecretory granules were also occasionally found. The behavior was variable: 36% of @entity1 developed @entity3 , especially to the liver. The adult @entity1 did poorly: three of five died of @entity5 (mean survival, 18 months), and two were alive at 5 and 15 months, respectively. In contrast, five of the six evaluable pediatric @entity1 were alive from 22 months to 22 years after diagnosis, and only one died of @entity5 after 16 months. Good responses to chemotherapy were noted in the pediatric group.
