Pediatric and Developmental Pathology

In this, part 2 of the histopathologic approach to the diagnosis of metabolic disease of the liver, the steatotic, cirrhotic, and neoplastic groups are addressed. See the previous issue, Volume 1, Number 3, of Pediatric and Developmental Pathology for part 1 [1]. The perspective concludes with a tabulated assessment of the likelihood of diagnostic ascertainment.

Primary malignant epithelial tumors of the liver (PMETL) are rare in the pediatric age group, and very little is known about their biology as compared with adult tumors. The prognostic value of the DNA contents measured by image analysis and expression of oncogene c-erb2 and tumor suppressor gene p53 were studied in 30 cases of PMETL in children, including 24 with hepatoblastomas (HB) and 6 with hepatocellular carcinomas (HCC). p53 overexpression was detected in 12 out of 26 cases (46.0%), or in 3 of 5 HCC and 9 of 21 HB cases. A relatively high concordance of staining was observed with the two antibodies used (clone DO7, Dako and clone DO1, Santa Cruz Biotechnology). c-erb-B2 did not yield the characteristic membrane staining in any of the 27 cases in which reliable staining was obtained. However, 1 out of 4 patients with HCC and 1 of 23 with HB revealed strong granular cytoplasmic staining in several neoplastic cells. Interestingly, these were two of the three aneuploid multiploid cases. DNA histograms of 13 out of 29 cases (54.8%) were classified as DNA aneuploid (5/6 HCC and 8/23 HB): nine were hyperdiploid, one was hypodiploid (1HB), and three were multiploid (2HB and 1HCC). In the HB group, DNA aneuploidy was strongly associated with embryonal histological areas, suggesting that a disturbance in the process of cell differentiation is associated with marked genetic aberrations. Only the group of HB was submitted to univariate analysis of survival by the Kaplan-Meier method for age (<24 months vs. ≥24 months), sex, preoperative chemotherapy (yes vs. no), residual disease (metastasis, and/or unresectable tumor), p53 expression by immunohistochemistry (positive vs. negative), and DNA ploidy (diploid vs. aneuploid). Only residual disease at the time of diagnosis (P< 0.017) and preoperative chemotherapy (0.030) were found to be negatively correlated with biological behavior, estimated as overall survival. DNA aneuploidy tumors (P < 0.125) and male patients (P = 0.123) showed a trend toward a more aggressive clinical behavior, although the difference was not statistically significant. Combining DNA ploidy and residual disease, patients were categorized into three groups: group I, patients with no adverse prognostic factors, i.e., diploid tumors without residual disease; group II, patients with only one adverse prognostic factor, i.e., aneuploid tumor or residual disease; and group III, patients with both adverse factors, aneuploid tumors and residual disease at time of diagnosis. A log-rank test comparing the three survival curves showed a statistically significant difference between them (P < 0.003). Although the series of cases is small, the results of this study highlight the importance of including DNA ploidy in the protocols designed for HB in children by international cooperative groups.

Cloacal dysgenesis is a rare malformation sequence. We studied cloacal dysgenesis in four fetuses, including three at 18–22 weeks of gestation. All four fetuses showed a smooth perineum with absence of anal, urethral, and/or vaginal openings. The urinary bladder was dilated in 3 cases. The labia majora and minora were absent in the two female fetuses; the scrotum and penis were absent in one male fetus and hypoplastic in the second. The kidneys were either absent (1 case), dysplastic (1 case), or hydronephrotic (1 case). Normal kidneys were seen in a fetus of 20–22 weeks gestation in whom the urinary obstruction was alleviated by a vesicocolonic fistula. This fetus did not have pulmonary hypoplasia.

Severe renal anomaly and pulmonary hypoplasia are the limiting factors for the survival of infants born with cloacal dysgenesis. The unique observation of normal kidneys and lungs in one of our fetuses, despite anhydramnios, suggests that the effect of oligohydramnios on lung development may be limited early in gestation, at least up to 20–22 weeks. It may also indirectly support the theory that there are factors other than oligohydramnios that interfere with early lung development, such as reduced production of a pulmonary growth factor by the kidney or reduced proline production by malformed kidneys, that may cause decreased collagen formation and result in hypoplastic lung mesenchyme.

A retrospective study of 1513 fetal postmortem examination reports from 1967 to 1996 yielded 35 cases with anomalous major pulmonary fissures (2.3%), to which a further 25 cases were added from fetal postmortem examinations performed between 1929 and 1966. Of 60 cases with anomalous fissures, 43 had an absent right horizontal fissure and 8 had a supernumerary left horizontal fissure; the remaining 9 showed various patterns in which one lung lacked major fissures. Histological examination in 29 cases did not reveal any additional pulmonary abnormality and pulmonary maturity was appropriate for gestational age. Additional malformations were present in 40 cases and these were frequently multiple, the most common being central nervous system, cardiovascular, and genitourinary system defects; notable heart malformations (10 cases); hydrocephalus (5 cases); and cystic renal dysplasia (4 cases). Chromosomal abnormalities were demonstrated in six cases although this figure does not reflect their prevalence, as many cases predate the availability of karyotyping. In seven cases, including three with polysplenia syndrome and one with situs inversus totalis, there was evidence of an underlying abnormality of left–right asymmetry, and in 13 cases there was documented pulmonary hypoplasia.

Melanotic neuroectodermal tumor of infancy is a rare but well-recognized entity in pediatric pathology. However, the relationship of this tumor to other pediatric small cell tumors with neuroectodermal features (such as neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, and desmoplastic small round cell tumor) is undetermined. Molecular genetic studies of melanotic neuroectodermal tumor of infancy have not been reported. We studied three typical cases of mela-notic neuroectodermal tumor of infancy in an attempt to link this tumor to other small cell tumors with well-characterized molecular genetic changes. Tests performed included: detection of MYCN gene amplification and deletion of 1p (all 3 cases), and presence of the t(11;22)(q24;q12) and the t(11;22)(p13;q12) translocations (2 of 3 cases). None of these tests yielded positive results. Thus, there is no genetic basis at present to link melanotic neuroectodermal tumor of infancy to neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, or desmoplastic small round cell tumor.

Deep granuloma annulare (DGA) is one of several lesions of skin and superficial soft tissues whose histologic character is a palisading granuloma with a small central focus of necrosis or necrobiosis. Unlike the other palisading necrobiotic lesions, DGA has a predilection for children in the first 5 to 6 years of life. A painless subcutaneous nodule(s) in the lower anterior tibial region or foot and the scalp, typically in the occiput, was the most common presenting feature in this study of 35 cases. Additional or recurrent lesions were reported in approximately 70% of cases with clinical follow-up. All lesions showed the presence of necrobiosis; however, one of the characteristic features was the multinodular character of the predominantly mononuclear cellular aggregates. The presence of vascular spaces at the periphery of the nodular profiles served as a clue to the diagnosis of DGA. The palisading arrangement of the mononuclear cells was evident only in those foci with central necrobiosis. A histiocytic disorder or fibrohistiocytic process was a common consideration in the differential diagnosis, especially in those cases with less apparent foci of necrosis. Palisading histiocytes with prominent eosinophilic cytoplasm and some nuclear atypism were problematic with regard to possible epithelioid sarcoma. Our study failed to identify any underlying or predisposing factors in the development of DGA. Despite the fact that DGA is a well-documented lesion in children, it occurs sufficiently infrequently that it is often not considered clinically when it presents as a subcutaneous mass or masses in a child. Its recognition by the pathologist is especially important as the occurrence of additional lesions in a high proportion of children can be anticipated without undue concern.

Retrospective review comparing the modified Dieterle stain with standard acid-fast stains was performed on seven surgical pathology cases that contained culture-positive mycobacteria infections. Tissues examined comprised cervical and submandibular lymph nodes and soft tissues of the face and chest. Modified Dieterle staining was performed on paraffin-embedded tissue sections, and the results were compared with those of hematoxylineosin stains and auramine-rhodamines and carbol-fuchsin acid-fast stains. The acid-fast stain showed organisms in three of seven cases on initial review and five of seven cases on retrospective review; the auramine-rhodamine stain retrospectively revealed organisms in five cases. In contrast, the Dieterle stain showed organisms in all seven sections on retrospective examination. Dieterle stains revealed either beaded bacilli or nocardia-like filamentous organisms, sometimes with abundant granular debris possibly representing degenerative organisms. In three cases in which bacteria were readily apparent with the Dieterle stain, only rare organisms could be identified with the acid-fast stain. The modified Dieterle stain was more sensitive than the acid-fast stain in the identification of mycobacteria in pediatric specimens, and its use is recommended in cases with necrotizing granulomas. However, its specificity is limited by morphologic similarities of the organisms to those of nocardiosis and cat scratch disease.

Cleidocranial dysplasia (CCD), an uncommon disorder involving membranous bones, is rarely lethal in early life. The calvaria is defective and wormian bones are present. Abnormalities of the clavicles vary in severity from a minor unilateral defect to bilateral absence. This report concerns pre- and postmortem anatomical and radiological findings in a 15-day-old female neonate with CCD. Her postnatal course was characterized by seizures and recognition of hydrocephalus during the first day of life. The calvaria was hypoplastic with numerous wormian bones. A pseudofracture of the right clavicle was present. Hydrocephalus was present in the brachycephalic brain which had a severely thinned cerebral cortex. Hemosiderin in the ventricular lining and marked subependymal gliosis were interpreted as evidence of old intraventricular hemorrhage that had occurred in utero. A CCD-related condition, Yunis-Varon syndrome (YVS), is noted for early lethality and for developmental and secondary abnormalities of the central nervous system. The present case only partially matches the phenotype of YVS and might represent a part of a spectrum of phenotypic variants ranging from viable CCD to lethal YVS.

Ataxia telangiectasia is an autosomal recessive neurologic disorder which is frequently associated with a deficiency of IgA immunoglobulin. We report an unusual case of monoclonal gammopathy of the IgA kappa type in a 2-year-old female patient newly diagnosed with ataxia telangiectasia. Quantitative analysis of the patient's immunoglobulins revealed a marked elevation in the IgA fraction with a value of 672 mg/dL (normal 14–123 mg/dL). The IgG and IgM fractions were normal. Serum protein electrophoresis showed a band of restricted mobility present in the gamma region, which was identified as a monoclonal IgA kappa immunoglobulin on immunofixation electrophoresis. This is the first case report of a patient with ataxia telangiectasia associated with an IgA monoclonal gammopathy.

A case of congenital thyroid teratoma with nodal spread is reported. Primary surgery was performed on a female infant on the 6th day of life. The thyroid mass was removed in toto, and an adjacent 1.2 cm lymph node was also removed. Histology showed solid and cystic teratoma with a variety of elements including prominent neuroglial tissue that was neuroblastoma-like in places. Residual compressed non-neoplastic thyroid tissue was identified in the subcapsular plane. The lymph node was largely replaced by neuroglial tissue that was cellular in some areas and showed intrasinusoidal growth and some mitotic activity. Recurrent cervical lymphadenopathy gradually developed, commencing a few months after surgery. Excision of cervical nodes was undertaken at 9 months of age. About 13 nodes up to 2 cm in diameter were excised. Most of the specimens consisted of reactive lymph nodes, but in three of the smaller nodes, there were subcapsular and sinusoidal masses of focally cellular neuroglial tissue, again with occasional mitoses. This tissue stained strongly for glial fibrillary acidic protein, in addition to expressing neural markers. The lymph node “deposits” were interpreted as “displaced” lesional tissue rather than metastases in the usual, aggressive sense. The girl remains well at 5 years of age.

The therapy for pediatric germ cell tumors has historically been widely variable and institution dependent. The efforts to provide consistent, biology-driven therapy through Intergroup protocols has been a relatively recent phenomenon that has provided the framework for future protocol designs. The first Intergroup protocols confirmed that stage I malignant testicular germ cell tumors and immature teratomas at all sites in children could be treated with surgery alone followed by close observation. Future protocols currently in the planning stages may extend this low-risk category to stage I ovarian germ cell tumors of all histologic types. Low-stage extragonadal germ cell tumors may be placed in a new intermediate risk category. Particular pathologic issues that were raised and reported during the first protocols and that may impact on future protocol design include the presence and size of foci of endodermal sinus tumors within low-stage immature teratomas at all sites. Accurate staging will grow more critical in future protocols. The ability to recruit international cooperative groups will determine the success of chemotherapy tailored to specific subgroups that now must be lumped for statistical purposes. Lastly, companion biologic studies will be critical to defining the different subtypes of germ cell tumors and to determining predictors of biologic behavior.