Insulin-like Growth Factor II mRNA-binding Protein 3 is a Highly Sensitive Marker for Intravascular Large B-cell Lymphoma: Immunohistochemical Analysis of 152 Pathology Specimens From 88 Patients.

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of aggressive extranodal large B-cell lymphoma characterized by the selective growth of lymphoma cells within the lumina of blood vessels, particularly capillaries. IVLBCL lacks mass formation, and its diagnosis can be challenging. We analyzed the utility of insulin-like growth factor II mRNA-binding protein 3 (IMP3) immunohistochemistry for IVLBCL diagnosis in various organs. Double staining with paired box 5 (PAX5) was performed for validation. Overall, 152 pathological specimens (111 positive and 41 negative for IVLBCL) obtained from 88 patients with a diagnosis of IVLBCL were stained for IMP3 and IMP3/PAX5. As negative controls, 40 pathology specimens from 38 patients with no history of IVLBCL or other B-cell lymphomas were stained for IMP3, which comprised 31 benign pathological specimens from 29 patients in whom malignancy was suspected, 7 cases of appendicitis with intravascular and/or intralymphatic lymphoid proliferations, and 2 cases of intravascular natural killer/T-cell lymphoma. All mononuclear cells with cytoplasmic staining were considered positive for IMP3 expression, but expression restricted to germinal center B cells was excluded from evaluation. All 111 IVLBCL pathological specimens were positive for IMP3 and IMP3/PAX5. In addition, 11 of the 41 specimens originally diagnosed as IVLBCL-negative showed IMP3/PAX5 double-positive cells, raising the suspicion of IVLBCL. However, of the 40 negative control samples, IMP3-positive non-germinal center B cells were detected in only 2 samples ( P = 0.0131) and no intravascular IMP3-positive B cells suspicious for IVLBCL were identified. Altogether, IMP3 immunohistochemistry is a highly sensitive marker of IVLBCL and can be a helpful adjunct for IVLBCL diagnosis.

Hemophagocytic lymphohistiocytosis associated with hepatocellular carcinoma.

A man in his 60s was admitted because of abdominal pain and fatigue. Contrast enhanced computed tomography (CECT) showed a hypovascular tumor, 7 cm in size, in the left lobe of liver. He had no history of alcohol consumption. HBs antigen and HCV antibody were negative. For definitive diagnosis, biopsy of the hepatic tumor was performed. After the biopsy, the patient suddenly got high fever, and blood tests showed WBC 22,000/L, Hb 8.9 g/dL, Plts 11.6 × 104/L, AST 140 IU/L, ALT 93 IU/L, LDH 635 U/L. He died on the following day despite of supportive therapy. Autopsy revealed that the hepatic tumor was poorly differentiated hepatocellular carcinoma (HCC) and that hemophagocytic macrophages were found in the bone marrow and spleen. Based on the pathological findings of autopsy, he was finally diagnosed with hemophagocytic lymphohistiocytosis (HLH) associated with HCC. HLH is a rare and life-threaded disorder of immune overactivation. Malignancy-associated HLH is well-known; however, it is usually associated with malignant lymphoma. To our knowledge, this is the first reported case of HLH associated with HCC, which was diagnosed by autopsy. Although extremely rare, our case highlights that HLH should be considered as a differential diagnosis of unknown high fever and bicytopenia in patients with solid tumors, including HCC.

A case of vasculogenic mesenchymal tumor in the mediastinum: whole-exome sequencing reveals origin from pre-existing germ cell tumor.

Vasculogenic mesenchymal tumor (VMT), a primitive mesenchymal neoplasm enriched by various-sized atypical vessels, is a new entity that develops in mediastinal germ cell tumors (GCTs) with yolk sac tumor (YST) components after chemotherapy. Notably, patients with VMT in the residual GCT have increased risk of developing sarcomas or hematopoietic malignancies. Here, we report a late-teenage male patient with residual teratoma and high-grade VMT after chemotherapy for a mediastinal mixed GCT, including YST. Whole-exome sequencing revealed biallelic inactivation of TP53 and extensive copy number alterations that suggested whole-genome doubling. The biopsy tissue of the mixed GCT before chemotherapy exhibited overlapping genetic alterations to those in the VMT. Immunohistochemical analyses of the VMT showed that the abnormal vessels were positive for cytokeratin, glypican 3, EZH2, and IMP3. The findings that VMT inherits the genetic alterations of pre-existing mixed GCT and exhibits a partly YST-like immunophenotype might contribute to its clinical aggressiveness.

Ovarian Mucinous Carcinoma with a Yolk sac Tumor-Like Component: A Report of Three Cases with a Literature Review for Prognostic Analysis.

The most common subtype of ovarian carcinoma associated with somatically derived yolk sac tumor (YST) is endometrioid carcinoma. Only two cases of ovarian mucinous carcinomas associated with YST have been reported; herein, we present three additional patients, along with a review of previous literature and our pathology archives to analyze the tumor prognosis. The patients' ages ranged from 38 to 53 years. Two patients had FIGO stage 1 tumors, and one patient had a stage 3 tumor. Two patients died of the disease within a year, and one patient survived with distant metastasis (32 months after surgery). In all three tumors, the YST-like component comprised less than 5% of the total tumor area. Together with the two previously reported mucinous carcinomas with a YST-like component, the prognosis of the five mucinous carcinomas with a YST-like component were compared with that of 19 conventional mucinous carcinomas resected at our hospital. The survival curves were estimated using the Kaplan-Meier method. As a result, the overall survival rate of patients with mucinous carcinomas with a YST-like component was significantly lower than that of patients with conventional mucinous carcinomas (P = .0014). Our study indicates that the presence of a YST-like component in mucinous carcinomas would be a strong prognostic indicator.

Maturing papillomatous nevoid melanoma in the scalp mimicking recurrent melanocytic nevus: A case report of previously undescribed subtype of nevoid melanoma.

Nevoid melanoma is a subtype of melanoma that histologically resembles a melanocytic nevus. Two subtypes have been proposed for nevoid melanoma, namely papillomatous and maturing. Here, we report the case of a 67-year-old woman who developed two nevoid melanomas on her scalp with composite histological features of papillomatous and maturing subtypes after electrocautery of a nearby solitary scalp papule. The histology of both lesions was very similar, papillary in shape, and both comprised two melanocyte populations, including large atypical melanocytes and small non-atypical melanocytes. Whole-exome sequencing was performed in one of the two lesions, which revealed a high mutation burden (17 mutations/megabase) with co-deletion of CDKN2A. Additional immunohistochemistry revealed that the large and small melanocytes in both lesions were completely negative for p16 and MTAP. A final diagnosis of nevoid melanoma was made. To our knowledge, this is the first report of a nevoid melanoma with both features of papillomatous and maturing subtypes. Pathologists should be aware of this subtype of melanoma to avoid misdiagnosis as a mitotically active melanocytic nevus. In this case, immunohistochemistry for p16 and MTAP, in addition to molecular analysis, helped in the final diagnosis.

The Expression of Insulin-Like Growth Factor 2 Messenger RNA-Binding Protein 3 in Langerhans Cell Histiocytosis and Langerhans Cell Sarcoma.

Langerhans cell neoplasms, which include Langerhans cell histiocytosis and Langerhans cell sarcoma, are tumors that originate from dendritic cells. Langerhans cell sarcoma is defined as a high-grade neoplasm with overtly malignant cytological features and the Langerhans cell-like phenotype, and generally has a poorer prognosis and more aggressive phenotype than Langerhans cell histiocytosis. Insulin-like growth factor 2 messenger RNA-binding protein 3 (IGF2BP3 or IMP3) is an oncofetal protein that is expressed in various cancer types; its expression is often associated with a poor prognosis and aggressive phenotype. Here, we used immunohistochemistry to evaluate IGF2BP3 expression in Langerhans cell neoplasms. IGF2BP3 expression was scored as negative (< 1%) or positive (≥ 1%) by immunohistochemistry. All 4 patients with Langerhans cell sarcoma (100%) and 6 of 22 pediatric (age < 18 years) patients with Langerhans cell histiocytosis (27.3%) had positive results for IGF2BP3; however, 16 of 22 pediatric patients with Langerhans cell histiocytosis (72.7%) and all 15 adult (age ≥ 18 years) patients with Langerhans cell histiocytosis (100%) had a negative result. Among patients with Langerhans cell histiocytosis, IGF2BP3 expression was independent of sex, location, prognosis, and BRAF V600E staining results. Taken together, these results indicate that IGF2BP3 expression may be a helpful marker for distinguishing Langerhans cell sarcoma from Langerhans cell histiocytosis in adult patients.