SUMMARY We describe a patient with an autoinflammatory disease in which the main clinical features are pustular rash, marked osteopenia, lytic bone lesions, respiratory insufficiency, and thrombosis. Genetic studies revealed a 175-kb homozygous deletion at chromosome 2q13, which encompasses several interleukin-1 family members, including the gene encoding the interleukin-1–receptor antagonist (IL1RN). Mononuclear cells, obtained from the patient and cultured, produced large amounts of inflammatory cytokines, with increasing amounts secreted after stimulation with lipopolysaccharide. A similar increase was not observed in peripheral-blood mononuclear cells from a patient with neonatal-onset multisystem inflammatory disorder (NOMID). Treatment with anakinra completely resolved the symptoms and lesions.

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in three infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (seven and twelve from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated-ERK, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, while CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, ten with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis, and provides guidance for the clinical management of this emerging histiocytic entity.

OBJECTIVE-Heterozygous activating mutations of glucokinase have been reported to cause hypoglycemia attributable to hyperinsulinism in a limited number of families. We report three children with de novo glucokinase hyperinsulinism mutations who displayed a spectrum of clinical phenotypes corresponding to marked differences in enzyme kinetics. RESEARCH DESIGN AND METHODS-Mutationswere directly sequenced, and mutants were expressed as glutathionyl S-transferase-glucokinase fusion proteins. Kinetic analysis of the enzymes included determinations of stability, activity index, the response to glucokinase activator drug, and the effect of glucokinase regulatory protein.RESULTS-Child 1 had an ins454A mutation, child 2 a W99L mutation, and child 3 an M197I mutation. Diazoxide treatment was effective in child 3 but ineffective in child 1 and only partially effective in child 2. Expression of the mutant glucokinase ins454A, W99L, and M197I enzymes revealed a continuum of high relative activity indexes in the three children (26, 8.9, and 3.1, respectively; wild type ϭ 1.0). Allosteric responses to inhibition by glucokinase regulatory protein and activation by the drug RO0281675 were impaired by the ins454A but unaffected by the M197I mutation. Estimated thresholds for glucose-stimulated insulin release were more severely reduced by the ins454A than the M197I mutation and intermediate in the W99L mutation (1.1, 3.5, and 2.2 mmol/l, respectively; wild type ϭ 5.0 mmol/l).CONCLUSIONS-These results confirm the potency of glucokinase as the pancreatic ␤-cell glucose sensor, and they demonstrate that responsiveness to diazoxide varies with genotype in glucokinase hyperinsulinism resulting in hypoglycemia, which can be more difficult to control than previously believed.

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Infants with congenital hyperinsulinism often require pancreatectomy. Recessive mutations of the ATP-dependent plasma membrane potassium channel (K(ATP)) genes, SUR1 and K(ir)6.2, cause diffuse hyperinsulinism. K(ATP) channel mutations can also cause focal disease through loss of heterozygosity for maternal 11p, resulting in expression of a paternal mutation. This study evaluated whether focal vs. diffuse hyperinsulinism could be diagnosed by acute insulin response (AIR) tests and whether arterial calcium stimulation/venous sampling (ASVS) could localize focal lesions. Fifty infants with diazoxide-unresponsive hyperinsulinism were studied. Focal lesions occurred in 70% of the cases. Positive AIR calcium occurred in 17 of 30 focal and 10 of 13 diffuse cases (P < 0.04). Positive AIR tolbutamide occurred in 27 of 30 focal vs. seven of 13 diffuse cases (P < 0.02); K(ATP) channel mutations were identified in four of the latter. ASVS localized the lesion in 24 of 33 focal cases (73%) but correctly diagnosed diffuse disease in only four of 13 cases. These results indicate that preoperative AIR tests do not distinguish focal vs. diffuse disease because some K(ATP) channel mutations retain responsiveness to tolbutamide. The ASVS test can be used to localize focal lesions in infants. The combination of ASVS, careful intraoperative histologic analysis, and surgical expertise succeeded in correcting hypoglycemia in 86% of the infants with focal hyperinsulinism.

Acid sphingomyelinase (sphingomyelin phosphodiesterase, EC 3.1.4.12) was purified from human urine and 12 tryptic peptides were microsequenced (128 residues). Based on regions of minimal codon redundancy, four oligonucleotide mixtures were synthesized and oligonucleotide mixture 1 (20mer; 256 mix) was used to screen 3 X 10(6) independent recombinants from a human fibroblast cDNA library. Putative positive clones (92) were purified and analyzed by Southern hybridization with oligonucleotide mixtures 2‐4. These studies revealed two groups of clones; group 1 (80 clones; inserts ranging from approximately 1.2 to 1.6 kb) hybridized with oligonucleotides mixtures 1‐4, while group II (12 clones; inserts ranging from approximately 1.2 to 1.4 kb) hybridized with oligonucleotide mixtures 1‐3. Several group II clones had larger inserts than those in group I, but did not hybridize with oligonucleotide mixture 4. Screening of a human placental cDNA library with a 450 bp group I fragment, also resulted in the isolation of group I and II clones. Representative clones from group I (pASM‐1) and group II (pASM‐2) were sequenced. pASM‐1 contained a 1879 bp insert which was colinear with 96 microsequenced amino acids, while the pASM‐2 1382 bp insert was colinear with 78 microsequenced residues. Notably, pASM‐2 did not have an internal 172 bp sequence encoding 57 amino acid residues, but had instead an in‐frame 40 bp sequence encoding 13 amino acids which was not present in pASM‐1. These findings demonstrate the presence of two distinct acid sphingomyelinase transcripts in human fibroblasts and placenta and suggest the occurrence of alternative processing of the mRNA encoding this lysosomal hydrolase.

The majority of the most severe cases of congenital hyperinsulinism (HI) are caused by defects in the beta-cell adenosine triphosphate (ATP)-sensitive potassium channel and usually require pancreatectomy to control blood sugar levels. In contrast to the recent advances in understanding the pathophysiology and genetic bases of HI, the histologic classification of this condition remains controversial. A recent proposal to classify the HI pancreata into diffuse and focal forms has drawn much interest because of its relative simplicity and its good correlation with the genetic abnormalities. We undertook a retrospective study to determine whether this classification scheme could be applied to 38 pancreata resected for HI at our institution. We also obtained leukocyte genomic DNA from 29 cases and screened the exons of ABCC8 and KCNJ11 genes for the presence of mutations. Nineteen cases (50.0%) were histologically classified as diffuse HI and 14 cases (36.8%) were categorized as focal form. The mutational analysis revealed that 14 of the 16 diffuse cases analyzed had either homozygous or compound heterozygous mutations of ABCC8 or KCNJ11 and 7 of 10 focal cases had only the paternally inherited mutations, consistent with the previous observations. Two patients (5.3%) had normal pancreatic histology but had persistent hypoglycemia postoperatively, leaving the possibility of residual focal lesion. Three of 38 cases (7.9%) did not fit well into either diffuse or focal category. Two cases differed from the described pattern for the diffuse form in that the nuclear enlargement was confined to a single area of the pancreas. The other case had a focal lesion but beta-cell nuclear enlargement was present in nonadjacent areas. Mutations for typical diffuse or focal HI were not identified in two of these three equivocal cases. We conclude from this study that nearly 90% of HI cases can be classified into either a diffuse or a focal form. However, a small percentage of cases represented a diagnostic challenge.

Congenital hyperinsulinism is a rare pancreatic endocrine cell disorder that has been categorized histologically into diffuse and focal forms. In focal hyperinsulinism, the pancreas contains a focus of endocrine cell adenomatous hyperplasia, and the patients have been reported to possess paternally inherited mutations of the ABCC8 and KCNJ11 genes, which encode subunits of an ATP-sensitive potassium channel (K ATP ). In addition, the hyperplastic endocrine cells show loss of maternal 11p15, where imprinted genes such as p57 kip2 reside. In order to evaluate whether all cases of focal hyperinsulinism are caused by this mechanism, 56 pancreatectomy specimens with focal hyperinsulinism were tested for the loss of maternal allele by two methods: immunohistochemistry for p57 kip2 (n ¼ 56) and microsatellite marker analysis (n ¼ 27). Additionally, 49 patients were analyzed for K ATP mutations. Out of 56 focal lesions, 48 demonstrated clear loss of p57 kip2 expression by immunohistochemistry. The other eight lesions similarly showed no nuclear labeling, but the available tissue was not ideal for definitive interpretation. Five of these eight patients had paternal K ATP mutations, of which four demonstrated loss of maternal 11p15 within the lesion by microsatellite marker analysis. All of the other three without a paternal K ATP mutation showed loss of maternal 11p15. K ATP mutation analysis identified 32/49 cases with paternal mutations. There were seven patients with nonmaternal mutations whose paternal DNA material was not available, and one patient with a mutation that was not present in either parent's DNA. These eight patients showed either loss of p57 kip2 expression or loss of maternal 11p15 region by microsatellite marker analysis, as did the remaining nine patients with no identifiable K ATP coding region mutations. The combined results from the immunohistochemical and molecular methods indicate that maternal 11p15 loss together with paternal K ATP mutation is the predominant causative mechanism of focal hyperinsulinism.