[Congenital spindle cell/sclerosing rhabdomyosarcoma: a clinicopathological analysis].

Objective: To investigate the clinicopathological features, immunophenotype and molecular genetic characteristics of congenital spindle cell/sclerosing rhabdomyosarcoma. Methods: Sixteen cases (including 10 consultation cases) of congenital spindle cell/sclerosing rhabdomyosarcoma diagnosed at the Beijing Children's Hospital, Capital Medical University, Beijing China, from April 2017 to January 2022 were collected. These cases were evaluated for clinical profiles, histomorphological features, immunophenotype and molecular characteristics. Results: Among the 16 patients, 9 were male and 7 were female. Five cases were present during maternal pregnancy and 11 cases were found immediately after birth. The tumors were located in the chest wall, low back, retroperitoneum, extremities or perineum. The tumors consisted of fasciculated spindle-shaped cells with localized mesenchymal sclerosis and vitreous metaplasia. Immunohistochemistry showed that the tumor cells expressed Desmin, Myogenin, MyoD1, SMA, CD56 and ALK to varying degrees, but not other markers such as CD34, CD99, pan-TRK, S-100 and BCOR. FISH analyses with NCOA2 (8q13) and VGLL2 (6q22) gene breakage probes revealed a breakage translocation in chromosome NCOA2 (8q13) in 4 cases (4/11). In the 6 cases subject to sequencing, a mutation at the p.L122R locus of MYOD1 gene was detected in 1 case (1/6). Two cases were examined by electron microscopy, which showed bundle-arranged myofilaments with some primitive myofilament formation. Five cases were resected with simple surgery, 2 cases were biopsied and followed up with observation only, and 9 cases were treated with surgery and adjuvant chemotherapy. Follow-up was available in 12 cases. At the end of the follow-up, 2 of the 12 patients developed local recurrences and 2 patients survived with disease. Conclusions: Congenital spindle cell/sclerosing rhabdomyosarcoma is a rare subtype of congenital rhabdomyosarcoma. It more commonly occurs in the chest, back and lower limbs of infants than other sites. NCOA2/VGLL2 gene fusion seems to be the most common genetic change. Its prognosis is better than other subtypes of rhabdomyosarcoma and those in adolescents and adults with the same subtype. Analysis and summary of its clinicopathological features can help differentiate it from other soft tissue tumors in infants and children and provide the information for appropriate treatments.

[Correlation of 1p/16q loss of heterozygosity and 1p gain with clinicopathological characteristics and prognosis in Wilms tumor].

Objective: To investigate the relationship between 1p/16q loss of heterozygosity (LOH) and 1p gain in Wilms tumor and their clinicopathologic characteristics and prognosis. Methods: A total of 175 Wilms tumor samples received from the Department of Pathology, Beijing Children's Hospital from September 2019 to August 2022 were retrospectively analyzed. The histopathologic type and presence of lymph node involvement were evaluated by two pathologists. The clinical data including patients'gender, age, tumor location, preoperative chemotherapy, and tumor stage were summarized. Fluorescence in situ hybridization (FISH) was done to detect 1p/16q LOH and 1p gain and their correlation with the clinicopathological features and prognosis were analyzed. Results: Among the 175 samples, 86 cases (49.1%) were male and 89 (50.9%) were female. The mean age was (3.5±2.9) years, and the median age was 2.6 years. There were 26 (14.9%) cases with 1p LOH, 28 (16.0%) cases with 16q LOH, 10 (5.7%) cases of LOH at both 1p and 16q, and 53 (30.3%) cases with 1q gain. 1q gain was significantly associated with 1p LOH (P<0.01) and 16q LOH (P<0.01). There were significant differences (P<0.01) between 1q gain, 1p LOH and 16q LOH among different age groups. The rate of 16q LOH in the high-risk histopathological subtype (50.0%) was significantly higher than that in the intermediate-risk subtype (13.6%, P<0.05). The frequency of 1q gain, 1p LOH, and 16q LOH in children with advanced clinical stages (Ⅲ and Ⅳ) was significantly higher than that in children with early clinical stages (Ⅰ and Ⅱ). 1q gain, 1p LOH, and 16q LOH showed no significant correlation with gender, unilateral or bilateral disease, chemotherapy, or lymph node metastasis. The progression-free survival (PFS) time for patients with 1q gain and 1p LOH was significantly shorter than those without these aberrations (P<0.05). Additionally, the PFS time of patients with 16q LOH was slightly shorter than those with normal 16q, although the difference was not statistically significant. Patients with stage Ⅲ to Ⅳ disease exhibiting 1q gain or 1p LOH had a significantly higher relative risk of recurrence, metastasis, and mortality. Conclusions: 1p/16q LOH and 1q gain are associated with age, high-risk histological type, and clinical stage in Wilms tumor. 1q gain and 1p LOH are significantly correlated with the prognosis of Wilms tumor.

[Hemolytic uremic syndrome complicated with IgA nephropathy: a clinicopathological study].

Objective: To investigate the clinicopathologic characteristics, treatments, outcomes and mechanisms of hemolytic uremic syndrome (HUS) complicated with IgA nephropathy (IgAN). Methods: The clinical manifestations, treatments, prognosis and histopathological features of renal biopsy tissues were analyzed in two cases of HUS complicated with IgAN from Beijing Children's Hospital, Capital Medical University using light microscopy, immunofluorescence detection and electron microscopy. The related literatures were also reviewed. Results: The clinical manifestations were microvascular hemolytic anemia, thrombocytopenia, acute renal impairment with hematuria, proteinuria, and positive anti-H factor antibody. Histological findings confirmed presence of both HUS and IgAN. Histological features included glomerular mesangial and stromal hyperplasia with endothelial cell proliferation, capillary stenosis, arteriolar thickening, and glomerular ischemia and capillary dilatation. Immunofluorescence detection showed diffuse IgA deposition in the glomerular mesangial matrix. Electron microscopy showed proliferation of mesangial and endothelial cells, thickening of the inner layer of the glomerular basement membrane, deposition of massive electronic densification in the mesangial region, and shrinkage of the segmental basement membrane. The two children were very responsive to plasma exchange and steroid treatments. However, their urine protein and occult blood tests remained continuously positive during the follow-up of 5 years 7 months and 8 months respectively. Conclusions: HUS complicated with IgAN is rare. The diagnosis relies on various pathological examinations, which require the combination of light microscopy, immunofluorescence detection and electron microscopy. Plasma exchange and steroid treatments are effective. However, the long-term prognosis is concerning and may relate to pathological grade and secondary factors. The mechanism of connecting HUS and IgAN is unknown, but may be caused by prodromal or secondary factors.

[Leydig cell hyperplasia of testis in children: a clinicopathological study].

Objective: To investigate the clinical, pathological features and differential diagnosis of testicular Leydig cell hyperplasia (LCH) . Methods: Clinical data, histological features, immunohistochemical findings, ultrastructural characteristics and follow-up data were analyzed in three cases of LCH. The cases were collected from 2011 to 2014 at Beijing Children's Hospital. A literature review was performed. Results: Two males (1.8 years and 2.9 years of age) showed isosexual pseudoprecocity with elevated serum testosterone. Imaging study showed bilateral testicular enlargement with multiple small nodules in the parenchyma. Another 13 years-old patient showed male pseudohermaphroditism and cryptorchism. Gross examination showed the bilateral markedly enlarged testis without discrete lesion. Histologically, LCH was seen in both nodular and diffuse patterns without destruction of seminiferous tubules. Adjacent spermatogenesis was noted. Immunohistochemically, the Leydig cells were positive for inhibin, calretinin and Melan A and ultrastructural analysis showed enriched cytoplasmic endoplasmic reticulum. Two cases had followed up for 7 years. One patient was symptom-free and one was stable. Conclusion: LCH is a rare benign condition, which is easily misinterpreted as testicular tumor or non-neoplastic diseases. Clinical presentation, imaging study and pathological evaluation are required for the diagnosis.

[Langerhans cell histiocytosis in children: clinicopathological and ultrastructural analyses of 345 cases].

Objective: To investigate the clinicopathological and ultrastructural characteristics of Langerhans cell histiocytosis (LCH) in children. Methods: A total of 345 cases of LCH from the Department of Pathology, Beijing Children Hospital from January 2012 to March 2016 were investigated by hematoxylin-eosin stain, EnVision immunohistochemistry and transmission electron microscopy. Results: The rate of primary clinical diagnosis of LCH in children was 46.0%(210/457). Among 345 patients of LCH, 213 were male and 132 were female, the male to female ratio was 1.6∶1.0, and the median age was 21 months (range from 2 days after birth to 13.3 years). There were total 597 lesions, including bony lesions (258, 43.2%), skin lesions (206, 34.5%) , followed by lymph node (16, 2.7%), lung (28, 4.7%), liver (25, 4.2%) and head-neck (50, 8.4%). Single organ system LCH (SS-LCH) was seen in 295 cases (85.5%) and 50 cases (14.5%) presented with multiple organ system involvement LCH (MS-LCH). There was no significant difference in age and gender between SS-LCH and MS-LCH groups. Regarding sites, more lesions were seen in bone and skin in SS-LCH group, in contrast lymph node, lung, liver and head-neck involvements were often seen in MS-LCH group. Immunohistochemically, the expression of CD1a and Langerin was seen in 99.7% (341/342) and 98.8% (338/342) of the cases respectively. The diagnostic rates by light and transmission electron microscopy were 98.8% (341/345) and 97.4% (112/115) respectively (P>0.05). Conclusions: LCH of children occurs predominantly in SS-LCH pattern, frequently involving bone, skin, lymph node, lung and liver and other sites with unique histopathological, immunophenotypical and ultrastructural features. Accurate diagnosis relies on the morphology, immunophenotype and ultrastructural features. Further refinement of specimen processing may improve the accuracy of pathological diagnosis.

Morphological changes of skeletal muscle, tendon and periosteum in the senescence-accelerated mouse (SAMP6): a murine model for senile osteoporosis.

SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. Previously we observed age-related changes of the bone in SAMP6. In the present study, we investigated the morphology of the skeletal muscle, tendon and periosteum in SAMP6 and age-matched normal mouse SAMR1. We did not find any significant differences between SAMR1 and SAMP6 at 1 and 2 months of age. As compared with SAMR1, the cross-sectional area of type I and type II muscle fibers of the soleus muscle were significantly low in SAMP6 at 8 months of age. The projections in the interface of the muscle-tendon junctions were significantly decreased in SAMP6 at 8 months of age. The number of fibroblasts and the diameter of the tendon collagen fibers in Achilles fiber were significantly reduced in SAMP6 at 8 months of age. The diameter of Sharpey's fiber reduced in SAMP6 at 5 and 8 months of age. Some chondrocytes in the insertions of Achilles tendon and some osteogenic cells in the periosteum showed degenerative changes in SAMP6 at 5 and 8 months of age. The pronounced degenerative changes were detected in the skeletal muscle, muscle-tendon junction, tendon, tendon-bone interface and periosteum in SAMP6 with age. These findings indicated the atrophy of skeletal muscle, degeneration of tendon and periosteum in SAMP6, which may be involved in the bone loss for senile osteoporosis.

Morphological study of the parathyroid gland and thyroid C cell in senescence-accelerated mouse (SAMP6), a murine model for senile osteoporosis.

SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. We investigated the morphology of the parathyroid gland and thyroid C cell, together with the serum parathyroid hormone (PTH) and calcitonin (CT) in SAMP6 and age-matched normal mice SAMR1. We did not find any significant differences between SAMR1 and SAMP6 at 1 month of age with regard to the serum PTH level and the morphology of the parathyroid glands. As compared with SAMR1, the serum PTH level was significantly higher in SAMP6 at 2, 5 and 12 months of age. In the parathyroid chief cells of SAMP6 at 2, 5 and 12 months of age, the Golgi complexes and the cisternae of the granular endoplasmic reticulum were well developed. Numerous secretory granules were located near the plasma membranes and mitoses were sometimes observed. There was no marked difference between SAMR1 and SAMP6 regarding the morphology of the thyroid C cells and the serum CT level. These findings suggest that the secretory activity of the parathyroid gland is stimulated in SAMP6 at 2, 5 and 12 months of age. The parathyroid follicle was sometimes found in SAMP6, and the significance of this structure was also discussed.