Spindle epithelial tumor with thymus-like elements is a rare thyroid lesion of children and young adults thought to be derived from branchial pouch remnants or foci of ectopic thymus. The lesion is poorly understood, and although it was originally believed to follow an indolent clinical course, its potential for late metastasis is becoming generally acknowledged. We have recently seen a unique case of this rare tumor in an 11-year-old boy, in which an unexpected and salient feature is the presence of a micrometastasis in a single lymph node at presentation. With the exception of 1 case with extensively infiltrative tumor and metastatic disease at the time of onset, in all other cases dissemination occurred years after surgical resection of the primary lesion. We review all previously reported cases and provide a detailed study of the histologic and ultrastructural appearances of this lesion.

The distinctive patterns of elastic fibers, best shown by the elastin immunostain, were helpful in evaluating melanomas associated with melanocytic nevi.

To measure discrepancies in diagnoses and recommendations impacting management of proliferative lesions of the breast, a questionnaire of five problem scenarios was distributed among over 300 practicing pathologists. Of the 230 respondents, 56.5% considered a partial cribriform proliferation within a duct adjacent to unequivocal ductal carcinoma in situ (DCIS) as atypical ductal hyperplasia (ADH), 37.7% of whom recommended reexcision if it were at a resection margin. Of the 43.5% who diagnosed the partially involved duct as DCIS, 28.0% would not recommend reexcision if the lesion were at a margin. When only five ducts had a partial cribriform proliferation, 35.7% considered it as DCIS, while if ≥20 ducts were so involved, this figure rose to 60.4%. When one duct with a complete cribriform pattern measured 0.5, 1.5, or 4 mm, a diagnosis of DCIS was made by 22.6, 31.3, and 94.8%, respectively. When multiple ducts with flat epithelial atypia were at a margin, 20.9% recommended reexcision. Much of these discrepancies arise from the artificial separation of ADH and low-grade DCIS and emphasize the need for combining these two under the umbrella designation of ductal intraepithelial neoplasia grade 1 (DIN 1) to diminish the impact of different terminologies applied to biologically similar lesions.

Primary epithelial tumors of the pancreas are extremely uncommon in children, and among these, acinar cell carcinoma (ACC) is the most rare. Here we describe our recent observations in the case of a 10-year-old boy with one of these exceptional examples. The histologic diagnosis of ACC was supported by both immunohistochemistry and electron microscopy. Despite its rarity, ACC should be kept in the differential diagnosis of pediatric pancreatic exocrine tumors. We also provide a comparison with an example of solid pseudopapillary tumor, another relatively infrequent epithelial tumor of the pancreas in the young. We review the relevant literature addressing the clinical and pathologic features of ACC and its distinction from other pancreatic neoplasms.