This ALK-positive anaplastic large cell lymphoma (ALCL) case highlights the importance of considering ALCL in the setting of iatrogenic immunosuppression in hidradenitis suppurativa patients. Diagnosis of ALCL can be challenging in situations with very low viability/cellularity, negative CD3 and/or other T-cell markers, and immunosuppression.

This is an unusual adult case of a metastatic well-differentiated neuroendocrine tumor with incidentally discovered subtle involvement of Langerhans cell histiocytosis (LCH), a clonal proliferation of Langerhans cells. It is important to recognize that LCH can often co-exist with other malignancies (solid > hematologic).

Epstein-Barr virus (EBV; human herpesvirus 4; HHV-4) and Kaposi sarcoma-associated herpesvirus (KSHV; human herpesvirus 8; HHV-8) are human gammaherpesviruses that have oncogenic properties. EBV is a lymphocryptovirus, whereas HHV-8/KSHV is a rhadinovirus. As lymphotropic viruses, EBV and KSHV are associated with several lymphoproliferative diseases or plasmacytic/plasmablastic neoplasms. Interestingly, these viruses can also infect epithelial cells causing carcinomas and, in the case of KSHV, endothelial cells, causing sarcoma. EBV is associated with Burkitt lymphoma, classic Hodgkin lymphoma, nasopharyngeal carcinoma, plasmablastic lymphoma, lymphomatoid granulomatosis, leiomyosarcoma, and subsets of diffuse large B-cell lymphoma, post-transplant lymphoproliferative disorder, and gastric carcinoma. KSHV is implicated in Kaposi sarcoma, primary effusion lymphoma, multicentric Castleman disease, and KSHV-positive diffuse large B-cell lymphoma. Pathogenesis by these two herpesviruses is intrinsically linked to viral proteins expressed during the lytic and latent lifecycles. This comprehensive review intends to provide an overview of the EBV and KSHV viral cycles, viral proteins that contribute to oncogenesis, and the current understanding of the pathogenesis and clinicopathology of their related neoplastic entities.

Interstitial deletion in the long arm of chromosome 9 [del(9q)] is a fairly common cytogenetic finding associated with acute myeloid leukemia (AML), seen in approximately 2-5% of AML patients. However, the genomic features of the deletion remain largely unknown. Using chromosome analysis, single nucleotide polymorphism microarray, and next-generation sequencing, we characterized del(9q)s and other genomic alterations in 9 AML patients. We found several distinct features of the del(9q)s. The proximal breakpoints of the deletions are clustered within a 2.5-Mb region (chr9: 68,513,625-70,984,372; GRCh37) enriched with segmental duplications, which may represent a "hotspot" for genomic rearrangements. However, the distal breakpoints of the deletions vary significantly. In addition, the overall deleted region could be divided into a 14.4-Mb proximal constitutional region (chr9: 70,950,015-85,397,699; 9q21.11q21.32) and a 24.0-Mb distal oncogenic region (chr9: 85,397,700-109,427,261; 9q21.32q31.1). We further identified a 6.8-Mb common overlapped deletion region (CODR) in the distal region (chr9: 90,590,650-97,366,400). This CODR carries multiple genes that are reportedly involved in cancer pathogenesis. The prognostic value of the del(9q) in AML apparently depends on additional genomic alterations in the patients.

Primary central nervous system lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin lymphoma that primarily arises in the brain, spinal cord, leptomeninges, and vitreoretinal compartment of the eye. The term is sometimes used interchangeably with primary central nervous system diffuse large B-cell lymphoma (PCNS DLBCL) because DLBCL comprises a great majority (90-95%) of PCNSL. Although rare, other types of lymphomas can be seen in the central nervous system (CNS), and familiarity with these entities will help their recognition and further workup in order to establish the diagnosis. The latter is especially important in the case of PCNSL where procurement of diagnostic specimen is often challenging and yields scant tissue. In this review, we will discuss the most common types of primary lymphomas that can be seen in the CNS with emphasis on the diagnostic histomorphologic, immunophenotypic, and molecular genetic features. The differential diagnostic approach to these cases and potential pitfalls will also be discussed.

Aims

Adenomatoid tumours are mesothelial-derived benign neoplasms with a predilection for the genital tract. Extragenital sites are rare and can cause significant diagnostic challenges. Herein, we describe the clinicopathological features of a cohort of adenomatoid tumours involving the gastrointestinal tract and liver in order to more clearly characterise their histological findings and aid in diagnosis.

Methods and results

The pathology databases at four institutions were searched for adenomatoid tumours involving the gastrointestinal tract or liver, yielding eight cases. Available clinicoradiological and follow-up data were collected from the medical records. Six tumours were incidentally discovered during imaging studies or at the time of surgical exploration for unrelated conditions; presenting symptoms were unknown in two patients. Histologically, the tumours were well-circumscribed, although focal ill-defined borders were present in four cases. No infiltration of adjacent structures was identified. Architectural heterogeneity was noted in five (63%) tumours; an adenoid pattern often predominated. The neoplastic cells were flattened to cuboidal with eosinophilic cytoplasm. Cytoplasmic vacuoles mimicking signet ring-like cells were present in five (63%) cases. Three (38%) cases showed involvement of the mesothelium with reactive mesothelial hyperplasia. Cytological atypia or increased mitotic activity was not identified. The surrounding stroma ranged from oedematous/myxoid to densely hyalinised. Immunohistochemistry confirmed mesothelial origin in all cases evaluated. No patients developed recurrence of disease.

Conclusions

The current study evaluates the clinicopathological findings in a collective series of gastrointestinal and hepatic adenomatoid tumours, correlating with those described in individually reported cases. We highlight common histological features and emphasise variable findings that could mimic a malignant neoplasm.

Introduction

Hepatolithiasis (intrahepatic stones) is rare in adolescent patients and requires complex management strategies to prevent recurrent infections and progression to hepatic fibrosis. Surgical management is often required. In cases of unclear etiology, further work-up is indicated to provide insight into future management. In this report we describe an extensive stone analysis.

Presentation of case

A 20-year-old Caucasian female presented with known hepatolithiasis and multiple prior recurrent bouts of abdominal pain requiring hospitalization. Magnetic resonance cholangiopancreatography (MRCP) demonstrated an abnormal left-sided hepatic biliary ductal system dilatation. She was treated surgically with a formal left hepatectomy and preservation of the caudate lobe. The right ductal system had no stones or evidence of inflammation, and her bile and stones cultures were negative for organism growth. An extensive analysis demonstrated stone composition primarily of cholesterol.

Discussion

Adolescent presentations of hepatolithiasis are rare and considerations in the differential diagnosis include primary sclerosing cholangitis, bile acid transporter defects, and other known genetic diseases. This case is unique because only the left half of the intrahepatic ductal system had evidence of stone disease and the bile was sterile. A detailed stone analysis demonstrating cholesterol supersaturation provides additional context though the etiology remains unclear in this case and will require lifelong follow-up.

Conclusion

Early-onset hepatolithiasis is rare and requires expert management, and in some cases definitive surgical management with life-long follow-up. Extensive stone analysis and genetic testing can be performed to help identify disease etiology in unique cases.

We present a case of oropharyngeal squamous cell carcinoma (SCC) of the tongue base incidentally detected on F-fluciclovine PET/CT. A 79-year-old man with history of locally advanced prostate cancer (Gleason score 4 + 5 = 9; cT2cN1M0) previously treated with androgen deprivation therapy (luprolide + bicalutamide) presented with a slowly rising serum prostate-specific antigen over 3 years, concerning for recurrent disease. F-fluciclovine PET/CT, obtained to identify potential sites of recurrence, demonstrated prostate bed uptake with possible left seminal vesicle involvement. Additionally, an exophytic, tracer-avid right tongue base mass was incidentally noted and later confirmed to be p16+ SCC on biopsy.