Thoracic SMARCA4-deficient undifferentiated tumour: Diagnostic challenges and potential for misdiagnosis in small tissue samples.

We report a diagnostically challenging case of a SMARCA4-deficient undifferentiated tumour to emphasize its potential to mimic other malignant tumours on histology, especially in small biopsies and where rhabdoid morphology is lacking. A 48-year-old man, who was known for chronic obstructive pulmonary disease and polysubstance use, presented with dyspnoea and an anterior mediastinal mass that had grown rapidly over a seven-month period. The rapid growth and location in the anterior mediastinum raised clinical suspicion for lymphoma or a germ cell tumour. Microscopic examination of a transthoracic, ultrasound-guided, core needle biopsy revealed relatively uniform, malignant epithelioid cells with clear cytoplasm, but lacking any rhabdoid features. Tumour necrosis was prominent. The immunohistochemistry panel was negative for lymphoma markers, but positive for SALL4 (a marker typically associated with germ cell tumours), CD34, EMA, and HepPar1, while expression of SMARCA4 and claudin-4 was entirely lost. Only focal cytokeratin expression was demonstrated. SMARCB1 (INI1) expression was retained. The diagnosis of SMARCA4-DUT was made based on these findings. Unfortunately, the tumour was already at an advanced stage at diagnosis (stage IVA) and the patient had a poor performance status. He was treated with palliative radiotherapy with no significant improvement in performance status and passed away 3 months after diagnosis. The case highlights the importance of considering SMARCA4-DUT in the differential diagnosis of an undifferentiated, rapidly growing thoracic tumour and the potential for misdiagnosis on a small tissue sample, particularly as rhabdoid morphology may be absent.

Syncope due to tracheal adenoid cystic carcinoma.

We present a case of a 34-year-old male who presented with syncope secondary to a large adenoid cystic carcinoma (ACC) of the distal trachea. A computed tomography and flexible bronchoscopy showed almost complete occlusion of the distal trachea. Resection with curative intent was performed, but resection margins were unfortunately not clear. The patient was subsequently offered adjuvant radiotherapy. Tracheal tumours comprise a small proportion of respiratory tract neoplasm, accounting for only about 2% of airway malignancies. Squamous cell carcinoma is the most common tracheal tumour, followed by ACC. Symptoms are usually attributable to the intraluminal component of the tumour causing an obstruction of the airway, resulting in stridor, dyspnoea, wheezing, haemoptysis, and cough. Syncope as a presenting symptom is exceedingly rare.

Papanicolaou induced fluorescence, Ziehl-Neelsen and Auramine O stains on lymph node fine needle aspiration biopsy specimens from children: A comparative study.

BACKGROUND: The rapid diagnosis of extrapulmonary tuberculosis in children remains challenging. The presence of enlarged lymph nodes provides an opportunity to obtain diagnostic material through fine needle aspiration biopsy (FNAB). Mycobacterial culture, traditionally the reference standard, has a slow turnaround time and PCR-based methods are not widely available in developing countries. Direct visualization of mycobacteria on microscopy can be a rapid method to confirm the diagnosis. This study compared three staining methods to visualize mycobacteria. METHODS: Hundred FNAB specimens from persistently enlarged lymph nodes in children, clinically suspicious for tuberculosis, were evaluated for the presence of mycobacteria by three staining methods: Papanicolaou induced fluorescence (PIF) and Auramine O staining using fluorescence microscopy and Ziehl-Neelsen (ZN) staining using conventional light microscopy. These methods were evaluated against mycobacterial culture. RESULTS: PIF positivity was 30%, with 38% and 48% for Auramine O and ZN respectively. The combined ZN/PIF positivity was 56%. The highest diagnostic accuracy (73%) was demonstrated by ZN alone and in combination with PIF, with PIF alone showing the lowest (49%) accuracy. Although the combined test showed the highest sensitivity, it had the lowest specificity, while ZN was significantly more sensitive than both other staining modalities. No statistical difference in specificity was seen among the tests. CONCLUSION: This study suggests that Auramine O staining on previously ZN stained slides does not significantly improve diagnostic accuracy. While currently widely available methods of direct visualization of mycobacteria suffer from low sensitivity, the ZN stain remains a useful diagnostic test, particularly in resource-constrained countries.

Colonic perineurioma (benign fibroblastic polyp): case report and review of the literature.

BACKGROUND: Colorectal perineuriomas are uncommon benign mucosal-based proliferations of mesenchymal cells that express perineurial markers, often associated with colonic crypts displaying a serrated/hyperplastic architecture. The vast majority of cases arise distal to the splenic flexure and have been described as sessile polyps. Using molecular analysis, BRAF mutations have been demonstrated in the serrated crypt epithelium. We report a new case of perineurioma presenting as a pedunculated polyp in the transverse colon, with prominent hemosiderin deposits in the uninvolved lamina propria that separated the perineurial proliferation from the surface epithelium, a previously unreported histological finding. By using immunohistochemistry, we demonstrated the presence of BRAF V600E mutated protein in the serrated crypt epithelium. In addition, a review of the literature on colorectal perineurioma is provided. CASE PRESENTATION: A 5 mm pedunculated polyp was removed from the transverse colon of a 42 year old man who presented with epigastric pain, weight loss and rectal bleeding. A proliferation of uniform plump spindled cells expanded the lamina propria and separated serrated colonic crypts. The epithelial component closely resembled microvesicular hyperplastic polyp. Immunohistochemical stains for epithelial membrane antigen (EMA), glucose transporter 1 (GLUT1) and collagen IV were positive in the stromal proliferation. A mutation-specific monoclonal antibody directed against BRAF V600E showed positive cytoplasmic staining in the serrated crypt epithelium but not in the perineurial proliferation. Conspicuous hemosiderin deposition was seen in the inflamed lamina propria between the perineurial proliferation and the surface epithelium. CONCLUSION: Although the majority of colorectal perineuriomas occur in the sigmoid colon and rectum and are described as sessile polyps, colorectal perineurioma can present as a pedunculated polyp proximal to the splenic flexure as described in this case. Conspicuous hemosiderin deposition can be seen in the superficial lamina propria. BRAF mutations are limited to the serrated crypt epithelium.

Fatal tumour pulmonary embolism.

A 30-year-old female with no significant past medical history was referred to our facility with sudden onset of shortness of breath. She had a low clinical probability for pulmonary thromboembolism and a computed tomography angiogram showed enlarged pulmonary arteries but no in situ thrombi. She developed recurrent episodes of hypotension and hypoxia, and was transferred to the intensive care unit where she died despite active resuscitation. An autopsy revealed extensive lymphatic and pulmonary vascular tumour emboli as the immediate cause of death. Pulmonary tumour embolism is a very rare cause of death, but can occur in patients who have an occult neoplasm.