We report on 11 cases of isochromosome 12p mosaicism (or Pallister mosaic aneuploidy syndrome) in which the isochromosome is usually absent in cultured lymphocytes but present in fibroblasts. The patients range in age from a 22-week-gestation fetus to a 45-year-old man. They have a distinct pattern of anomalies which enables one to make a diagnosis based on clinical manifestations alone. Craniofacial manifestations include "coarse" face with prominent forehead, sparsity of scalp hair, hypertelorism, epicanthal folds, flat bridge of nose, and highly arched palate. Affected newborn infants are profoundly hypotonic with sparsity of scalp hair especially bitemporally and a prominent forehead. Most have accessory nipples. Birthweight and growth parameters are usually normal; however, some newborn infants are unusually large. In infancy, the facial appearance becomes "coarse," hypotonia persists, and seizures may occur. As adults, growth may be normal, scalp hair is thicker and the mandible becomes prominent. Most have a generalized pigmentary dysplasia which may be evident with a Wood's lamp only. All cases have been sporadic and there is no consistent pattern of advanced parental age.

Testicular Leydig cell hyperplasia was observed in two brothers presenting with progressive sexual precocity at 2 yr of age. Virilization was shown to result from increased secretion rather than decreased clearance of gonadal testosterone. Testosterone hypersecretion appeared to be gonadotropin independent, as basal and gonadotropin-releasing hormone-induced serum LH concentrations were low by both RIA and bioassay. Adrenal steroidogenesis was demonstrated to be normal by ACTH stimulation, dexamethasone suppression, and split adrenal venous function tests. Testicular histology revealed immature reproductive structures in the 2 yr old, but advanced spermatogenesis in the 3 yr-old brother. The etiology of both Leydig cell hyperplasia and reproductive testicular maturation in the absence of significant gonadotropin secretion remains to be established.

Four cases of fetal teratomas arising from the sacrococcygeal and oropharyngeal areas are reported. The diagnosis, method of management, and grade of tumor are compared with previous experience in the literature. Pharyngeal lesions carry a worse prognosis for survival compared to the more common sacrococcygeal type (SCT). Atraumatic delivery and early repair of the lesion contribute to prolonged survival and lack of complications in cases of sacrococcygeal teratomas.

Lipoblastoma is a rare benign neoplasm of fetal-embryonal fat tissue with a 14% tendency to recur. It occurs almost exclusively in infants and children. To my knowledge, less than 100 cases, including children and adults, have been reported in the English literature. Two retroperitoneal and one case of mesenteric lipoblastoma, all presenting as a large palpable abdominal mass, are described. Our patients, aged 12 years, 7 months, and 11 months, were treated by total surgical excision of the tumors. They are alive and well 5, 4, and 3 years postoperative, respectively, with no evidence of recurrence and no indication for any adjunctive therapy. Pathologic evaluation was decisive for the best treatment and prognosis.