Rosai Dorfman Disease with malignant transformation to Histiocytic Sarcoma: A diagnostic conundrum.

ABSTRACT: Histiocytic disorders mostly occur as de-novo nodal or extranodal benign masses with rare secondary malignant transformation. A 10-year-old female presented with 10-cm cervical swelling since 9 months associated with fever. Computed tomography revealed left cervical lymphadenopathy and bilateral lung nodules. Lymph node excision biopsy showed effacement of architecture by atypical histiocytes with marked nuclear pleomorphism and frequent mitosis. Focal areas showed mature histiocytes with emperipolesis. The cells were immunopositive for CD68, CD163, and S100 (focal), whereas they were negative for Langerin and CD1a. The Ki67 proliferative index was 30%. A diagnosis of histiocytic sarcoma in a background of Rosai-Dorfman disease was made.

Pleural effusion supernatant: a reliable resource for cell-free DNA in molecular testing of lung cancer.

INTRODUCTION: DNA extracted from malignant pleural effusion (PE) sediments is the traditional source of tumor DNA for predictive biomarker molecular testing (MT). Few recent studies have proposed the utility of cell-free DNA (cfDNA) extracted from effusion cytology centrifuged supernatants (CCS) in MT. The aim of this study was to assess the feasibility and utility of molecular testing on cfDNA extracted from PE CCS in lung cancer patients. MATERIALS AND METHODS: The study was of prospective design. All PE CCS were collected and stored. Subsequently, in patients confirmed as primary lung adenocarcinoma (LUAD) and where patient matched effusion sediment/tissue biopsy/plasma was being tested for EGFR mutations, cfDNA extraction and EGFR MT by real-time polymerase chain reaction (qPCR) were performed. Custom panel targeted next-generation sequencing (NGS) (Ion Torrent; Thermo Fisher, Carlsbad, CA) was also performed wherever feasible. RESULTS: Out of 299 PE CCS collected, 20 CCS samples were included in the study. Concordant EGFR mutations were detected in pleural effusion CCS of 10 of 11 (91%) EGFR mutant cases as per qPCR performed on the matched sediment DNA (n = 8), lung biopsy (n = 2), and plasma (n = 1) samples. In 1 positive sample, CCS detected additional EGFR T790M mutation. Among 10 CCS samples also tested by NGS, additional EGFR mutations missed by qPCR were picked up in 2 (2 of 10). Success of mutation detection in CCS cfDNA did not correlate with cfDNA quantity or tumor fraction in sediment. CONCLUSIONS: cfDNA from effusion CCS is a reliable and independent source of tumor DNA highly amenable for MT and complement results from other tumor DNA sources for comprehensive mutation profiling in LUAD patients.

Chronic active Epstein-Barr virus infection mimicking tuberculosis - A diagnostic enigma.

ABSTRACT: Chronic active EBV infection is a rare disorder prone for misdiagnosis. They present with a wide range of symptoms from indolent to aggressive clinical course. Clinico-pathological correlation with confirmation by ancillary techniques is inevitable to diagnose this disease. We present a case of a 29-year-old male with fever, weight loss, and lymphadenopathy for 6 months. Lymph node biopsy showed occasional granuloma with preserved architecture. Suspected to have tuberculosis, he received antitubercular treatment (ATT) with no response for 3 months. Subsequently, additional workup showed many EBV-positive cells in sinusoids with high serum EBV titer, confirming the difficult diagnosis of CAEBV. The present case highlights the difficulty in the diagnosis of this entity and also emphasizes the necessity to recognize this disorder in countries endemic for tuberculosis, as it is no longer bound by ethnicity and geographical boundaries.

Schwannoma of Common Bile Duct: A Clinico-Radiologic Diagnostic Quagmire - A Case Report.

Background: Schwannomas are benign nerve sheath tumors that are extremely rare in the biliary tract. A comprehensive review of literature enumerated approximately 30 case reports of schwannoma in the biliary tract tree and porta hepatis region. Case Presentation: We report a case of a 40-year-old female who presented with abdominal pain. Imaging revealed a mass at the porta hepatis extending from the portal bifurcation till the hilum encasing the main portal vein and abutting the right portal vein. Differentials of carcinoma, lymphoma, and mesenchymal tumor were kept. Ultrasound-guided biopsy of the mass showed a benign nerve sheath tumor, immunopositive for S100. The histopathological evaluation of the excised mass confirmed the origin of mass in the common bile duct. Conclusions: Our case highlights that schwannomas, though benign, can mimic a carcinoma or lymphoma if present at a rare site such as bile ducts. An exhaustive clinical and radiological workup with diligent histopathological evaluation is mandatory in dealing with such rare cases as radical surgery and chemotherapy can be avoided in such patients.

Introdução: Os schwannomas são tumores benignos da bainhas nervosas, que são extremamente raros ao nível das vias biliares. Uma revisão abrangente da literatura enumerou cerca de 30 casos de schwannomas com envolvimento da árvore biliar e da região da Porta Hepatis. Apresentação do caso: Relatamos um caso de uma doente de 40 anos que apresentava dor abdominal. A imagem revelou uma massa que se prolonga desde a bifurcação da veia porta até ao hilo hepático, com "encasement" da veia porta principal e "abutement" da veia porta direita. Foram considerados os diagnósticos diferenciais de carcinoma, linfoma e tumor mesenquimatoso. A biópsia guiada por ecografia da massa mostrou um tumor benigno da bainha nervosa, imunopositivo para o S100. A avaliação histopatológica da massa excisada confirmou a sua origem na via biliar comum. Conclusões: O nosso caso realça que os schwannomas, embora benignos, podem imitar um carcinoma ou linfoma se estiverem presentes num local raro, como os canais biliares. Um trabalho clínico e radiológico exaustivo com uma avaliação histopatológica diligente é obrigatória para orientar com casos tão raros, em que a cirurgia radical e a quimioterapia podem ser evitadas.