Lipoblastomas presenting in older children and adults: analysis of 22 cases with identification of novel PLAG1 fusion partners.

Lipoblastomas are benign neoplasms of embryonal white fat that typically present in the first 3 years of life and show a lobular arrangement of maturing adipocytes with variable degrees of myxoid change. We systematically studied the clinicopathologic and genetic features of lipoblastomas arising in older children and adults. Cases with a diagnosis of lipoblastoma or maturing lipoblastoma in patients >3 years of age were retrieved from our archives. Immunostaining for CD34 and desmin and molecular studies (FISH, RNA sequencing) were performed. Twenty-two cases (8F; 14M) were identified in patients ranging from 4 to 44 years of age (median 10 years). Sites included extremity (n = 15), head and neck (n = 4), and trunk (n = 3) with tumor sizes varying from 1.6 to 17.5 cm (median 5). Only three tumors had histologic features of "conventional" lipoblastoma. The majority of tumors (n = 14) were composed of variably sized lobules of mature adipose tissue partitioned by thin fibrous septa ("maturing"). The remaining five cases consisted predominantly of bland spindled to plump ovoid cells embedded in a fibrous stroma, with a vaguely plexiform arrangement of small myxoid and adipocytic nodules ("fibroblastic"). CD34 was diffusely positive in all cases tested (21/21), while desmin immunoreactivity was identified in 12 of 21 cases (diffuse = 7, focal = 5). PLAG1 rearrangements were identified in 13 tumors in the entire cohort (59%), including all 5 fibroblastic tumors. RNA sequencing detected eight PLAG1 fusion partners, of which two were known (CHCHD7 and COL3A1) and six were novel (SRSF3, HNRNPC, PCMTD1, YWHAZ, CTDSP2, and PPP2R2A). Twelve cases had follow-up (1-107 months; median 21 months), and no recurrences were reported. Lipoblastomas may occur in older children and adults and may be difficult to recognize due to their predominantly adipocytic or fibrous appearance. Awareness that lipoblastomas may occur in older patients, careful evaluation for foci showing more typical morphologic features, ancillary immunohistochemistry for CD34 and desmin, and molecular genetic studies to identify PLAG1 rearrangements are the keys to recognizing these tumors.

Update on chemotherapeutic agents utilized for perioperative intraperitoneal chemotherapy.

A new strategy currently under evaluation in patients with peritoneal carcinomatosis from gastrointestinal and gynecologic cancers is perioperative intraperitoneal chemotherapy. Although results to date show benefit to carefully selected groups of patients, continued local-regional failure is seen in many treated patients. Continued clinical and laboratory research efforts to improve local-regional effects are desired. The chemotherapeutic agents that have been used in the past or are currently being tested were reviewed. Their pharmacologic properties and clinical features were collected from the medical literature and are reviewed in the text. An organized presentation of available data concerning the drugs available for perioperative intraperitoneal chemotherapy for peritoneal surface malignancy was made. From this review, new possibilities for improved doses, schedules, and drug combinations for perioperative intraperitoneal chemotherapy may become important in future clinical studies. Continued optimal utilization of intraperitoneal chemotherapy treatments in the operating room with hyperthermia or normothermic treatment in the early postoperative period is desirable. Innovative treatment strategies can improve the outcome of patients with peritoneal surface malignancy.