Estrogen Receptor Expression in DICER1-related Lesions is Associated with the Presence of Cystic Components.

DICER1 tumor predisposition syndrome results from pathogenic variants in DICER1 and is associated with a variety of benign and malignant lesions, typically involving kidney, lung, and female reproductive system. Over 70% of sarcomas in DICER1 tumor predisposition syndrome occur in females. Notably, pediatric cystic nephroma (pCN), a classic DICER1 tumor predisposition syndrome lesion, shows estrogen receptor (ER) expression in stromal cells. There are also renal, hepatic, and pancreatic lesions unassociated with DICER1 tumor predisposition syndrome that have an adult female predominance and are characterized/defined by ER-positive stromal cells. Except for pCN, the expression of ER in DICER1-associated lesions remains uninvestigated. In the present study, ER expression was assessed by immunohistochemistry in 89 cases of DICER1-related lesions and 44 lesions lacking DICER1 pathogenic variants. Expression was seen in stromal cells in pCN and pleuropulmonary blastoma (PPB) types I and Ir, whereas anaplastic sarcoma of kidney and PPB types II and III were typically negative, as were other solid tumors of non-Müllerian origin. ER expression was unrelated to the sex or age of the patient. Expression of ER showed an inverse relationship to preferentially expressed antigen in melanoma (PRAME) expression; as lesions progressed from cystic to solid (pCN/anaplastic sarcoma of kidney, and PPB types I to III), ER expression was lost and (PRAME) expression increased. Thus, in DICER1 tumor predisposition syndrome, there is no evidence that non-Müllerian tumors are hormonally driven and antiestrogen therapy is not predicted to be beneficial. Lesions not associated with DICER1 pathogenic variants also showed ER-positive stromal cells, including cystic pulmonary airway malformations, cystic renal dysplasia, and simple renal cysts in adult kidneys. ER expression in stromal cells is not a feature of DICER1 perturbation but rather is related to the presence of cystic components.

Detection of EGFR T790M mutation using liquid biopsy for non-small cell lung cancer: Utility of droplet digital polymerase chain reaction vs. cobas real-time polymerase chain reaction.

BACKGROUND: Digital platforms for mutation detection yield higher sensitivity than non-digital platforms but lack universal positive cut-off values that correlate with the outcome of osimertinib treatment. This study determined compared droplet digital polymerase chain reaction (ddPCR) to the standard cobas assay for epithelial growth factor receptor (EGFR) T790M mutation detection in patients with non-small cell lung cancer. METHODS: Study patients had EGFR-mutant tumours with disease progression on first/second generation EGFR tyrosine kinase inhibitors, and osimertinib treatment after T790M mutation detection. T790M status was tested by cobas assay using liquid biopsy, and only by ddPCR if an EGFR mutation was identified but T790M was negative. Clinical efficacy of osimertinib was compared between patients with T790M detected by cobas vs. only by ddPCR. A positive cut-off value for ddPCR was determined by assessing efficacy with osimertinib. RESULTS: 61 patients had tumors with an acquired T790M mutation, 38 detected by cobas and an additional 23 only by ddPCR. The median progression-free survival (PFS) for the cobas- and ddPCR-positive groups was 9.5 and 7.8 months, respectively (p=0.43). For ddPCR, a fractional abundance (FA) of 0.1% was used as a cut-off value. The median PFS of patients with FA ≥0.1% and <0.1% was 8.3 and 4.6 months, respectively (p=0.08). FA ≥0.1% was independently associated with a longer PFS. CONCLUSION: Using ddPCR to follow up the cobas assay yielded more cases (38% of total) with a T790M mutation. A cut-off value of FA ≥0.1% identified patients who responded as well to osimertinib as those identified by cobas assay. This sequential approach should detect additional patients who might benefit from osimertinib treatment.

Fine needle aspiration of spindle cell lipoma-Lochkern cells as a clue for diagnosis: A case arising in the parotid gland.

Spindle cell lipoma (SCL) is a rare form of lipoma, typically occurring as a mass in the back, shoulder or posterior neck of adult males. Most cases present little diagnostic difficulty on fine needle aspiration (FNA), but can be problematic when the SCL is in an unusual location. The authors report a case in the parotid gland in a 75-year-old man. FNA was paucicellular and showed loose collections of spindle cells with mild to moderate atypia, admixed with ropy collagen fibers on a myxoid background. The nuclei showed occasional angulation, interpreted on FNA as suspicious for myoepithelial tumor or low-grade sarcoma. The subsequent excisional specimen was diagnosed as SCL. On retrospective review of the FNA, an additional finding was recognized: 'naked' nuclei with intranuclear lipid vacuoles and positive immunostaining for S100 protein, consistent with Lochkern cells of mature adipocytes. This case highlights the challenges of diagnosing SCL on cytology when no fat-containing cells are apparent on the smear, and stresses the significance of Lochkern cells as a clue for diagnosis.

Acantholytic squamous cell carcinoma mimicking epithelioid angiosarcoma: A diagnostic challenge by cytology.

Squamous cell carcinoma (SCC) is the most common malignancy of the head and neck region. Most cases present little diagnostic difficulty on fine needle aspiration (FNA), but unusual variants can be problematic. The authors report a case of the acantholytic SCC of the oral cavity in a 36-year-old male. The FNA showed hypercellularity, with malignant cells arranged in isolation, loosely cohesive groups and a linear configuration. Such cells were round to elongated, with vesicular nuclei and prominent nucleoli. Cells possessed occasional intracytoplasmic vacuoles, misinterpreted on FNA to be vasoformative features as seen in malignant endothelial cells. The cytologic diagnosis was "positive for malignancy, suggestive of angiosarcoma". A total excision was performed and by histology, the tumor was diagnosed as acantholytic SCC. The malignant cells were positive by immunostaining for AE1/AE3, p40, p63 and vimentin, but negative for CD31, CD34 and ERG. The intracytoplasmic vacuoles were PAS- and mucin-negative and negative for the above antibodies. Testing for HPV (molecular and p16 immunostaining) was negative. This case highlights the diagnostic challenges on cytology when malignant acantholytic squamous cells show intracytoplasmic vacuoles, and stresses how immunohistochemistry is important for distinguishing acantholytic SCC from other mimics.

Placenta-Derived Extracellular Vesicles in Pregnancy Complications and Prospects on a Liquid Biopsy for Hemoglobin Bart's Disease.

Extracellular vesicles (EVs) are nano-scaled vesicles released from all cell types into extracellular fluids and specifically contain signature molecules of the original cells and tissues, including the placenta. Placenta-derived EVs can be detected in maternal circulation at as early as six weeks of gestation, and their release can be triggered by the oxygen level and glucose concentration. Placental-associated complications such as preeclampsia, fetal growth restriction, and gestational diabetes have alterations in placenta-derived EVs in maternal plasma, and this can be used as a liquid biopsy for the diagnosis, prediction, and monitoring of such pregnancy complications. Alpha-thalassemia major ("homozygous alpha-thalassemia-1") or hemoglobin Bart's disease is the most severe form of thalassemia disease, and this condition is lethal for the fetus. Women with Bart's hydrops fetalis demonstrate signs of placental hypoxia and placentomegaly, thereby placenta-derived EVs provide an opportunity for a non-invasive liquid biopsy of this lethal condition. In this article, we introduced clinical features and current diagnostic markers of Bart's hydrops fetalis, extensively summarize the characteristics and biology of placenta-derived EVs, and discuss the challenges and opportunities of placenta-derived EVs as part of diagnostic tests for placental complications focusing on Bart's hydrop fetalis.

Glioblastoma with novel EGFR mutations (T790M and exon 20 insertion) yet unresponsive to osimertinib: A case report.

Glioblastoma (GBM) is a high-grade adult-type IDH-wildtype diffuse glioma, commonly harboring epidermal growth factor receptor (EGFR) amplification. Here, we describe a case of a 49-year-old man with a GBM harboring a TERT promoter mutation. Despite surgical and chemoradiation therapy, the tumor recurred. At that time, comprehensive genomic profiling by next-generation sequencing identified two rare mutations in EGFR: T790M and an exon 20 insertion. Based on these findings, the patient elected to undergo off-label therapy with osimertinib, a third-generation EGFR tyrosine kinase inhibitor that has shown promising results in non-small cell lung carcinoma, including metastatic to brain, with exactly the same EGFR mutations. Moreover, the drug has excellent central nervous system penetration. Even so, no clinical response was observed, and the patient succumbed to the disease. The lack of response may be related to the specific nature of the EGFR mutations, and/or other unfavorable tumor biology overriding any benefit from osimertinib.

Multisystem inflammatory syndrome in children (MIS-C) showing disseminated aspergillosis, cytomegalovirus reactivation and persistent SARS-COV-2: Case report with autopsy review.

Multisystem inflammatory syndrome in children (MIS-C) is an emerging phenomenon associated with SARS-COV-2 infection (COVID-19) occurring in < 1 % of infected children. MIS-C is characterized by a hyperinflammatory state with excessive cytokine release ('storm') leading to hemodynamic compromise and multiorgan failure, with a death rate of ∼2 %. Autopsy examination can play a particularly important role in helping to understand the pathogenesis of MIS-C. Yet, only five autopsy studies have been reported to date. We report a fatal case of MIS-C involving a previously healthy, 5-year-old Thai boy admitted with MIS-C, one month after exposure to SARS-COV-2. While in intensive care, he was found to have a hypertrophic cardiomyopathy, and despite immunosuppressive treatment for MIS-C, developed shock and died. Multiorgan inflammation was not found at autopsy, implying that the MIS-C had responded to treatment. However, there was disseminated aspergillosis and cytomegalovirus reactivation, attributed to the immunosuppression. SARS-COV-2 virus was also found in multiple organs. To the best of our knowledge, this is the first reported autopsy of an MIS-C patient from Asia, and the first report of aspergillosis in MIS-C. This case underscores that the risks of immunosuppression are also a concern in MIS-C. Although MIS-C is generally considered to be a post-infectious hyperimmune reaction, persistence of SARS-COV-2 is a feature in all autopsies of MIS-C patients reported to date, suggesting a possible role in the pathogenesis, at least in fatal cases.

Pediatric fibromyxoid tumor with PLAG1 fusion: An emerging entity with a novel intracranial location.

Translocations involving PLAG1 occur in several tumors, most commonly pleomorphic adenoma and lipoblastoma. Recently, a distinctive soft tissue tumor with a PLAG1 fusion has been reported in the pediatric age group. These are low grade tumors with a fibroblastic or mixed fibroblastic and myxoid morphology but no other lines of differentiation. They are typically immunopositive for desmin and CD34. The partner genes for these tumors have included YWHAZ, EEF1A1, ZFHX4l, CHCHD7, and PCMTD1. We report another case of this fibromyxoid tumor with a PLAG1 fusion, this time with COL3A1 as the partner gene. The fusion placed expression of a full-length PLAG1 protein under the control of the constitutively active COL3A1 promoter. Overexpression of PLAG1 was confirmed by diffusely positive immunostaining for PLAG1. The most novel aspect of this tumor is the intracranial location. Opinion has been divided over whether these tumors are a specific entity, or related to lipoblastoma, since that tumor also typically occurs in soft tissue in the pediatric age group and shows many of the same gene fusions. However, lipoblastoma has never been reported in an intracranial location and, thus, our case provides compelling evidence that this fibromyxoid tumor is indeed a distinct entity.

Placental Findings Contributing to Perinatal Death: A 15-Year Retrospective Review from a Teaching Hospital in Thailand.

Introduction: The placenta is infrequently examined in developing countries. This study examined the role of placental pathology in perinatal deaths at Chulalongkorn University Hospital, Bangkok. Methods: Included were singleton intrauterine deaths after gestational week 20 and live-born infants up to 1 week old, over a 15-year period. Placental lesions were classified as: inflammatory-immune, maternal stromal-vascular, fetal stromal-vascular, umbilical cord complications and other. Results: 208 such cases had the placenta available. A placental cause of death was found in 96 (46%), non-placental causes in 28% and the cause of death was unknown in 26%. Of those 96 placentas, 44% were categorized as inflammatory-immune, 30% maternal stromal-vascular, 13% fetal stromal-vascular, 7% umbilical cord complications and 6% other. Conclusions: Placental causes of death were less common than in many Western studies, but inflammatory-immune processes more common. These differences may relate to how cases were accrued, and/or local socioeconomic factors, and warrant further study.

Combined Placental Maternal Floor Infarction and Cytomegalovirus Placentitis: A Case Report.

BackgroundMaternal floor infarction (MFI) and massive perivillous fibrin deposition (MPFD) are uncommon, related placental conditions secondary to trophoblastic cell damage. The etiology is unknown but MPFD/MFI is associated with adverse obstetric outcome and a significant risk of recurrence. Case report: We report a case of MPFD/MFI associated with cytomegalovirus (CMV) placentitis. A 27-year-old mother delivered a stillborn male fetus with a postmortem diagnosis of congenital CMV. The placenta showed a lymphohistiocytic villitis with isolated CMV inclusions, in combination with MFI. The villitis had features intermediate between CMV placentitis and villitis of unknown etiology (VUE). Conclusion: VUE is considered to be a maternal anti-fetal immune reaction resembling allograft rejection. We postulate that the viral infection in our case may have triggered this immune response, given that CMV antigens are known to cross react with some human antigens, in particular HLA. The subsequent trophoblastic cell damage could then lead to MFI/MFPD.

Simplified approach for pathological diagnosis of diffuse gliomas in adult patients.

The most recent WHO classification (2016) for gliomas introduced integrated diagnoses requiring both phenotypic and genotypic data. This approach presents difficulties for countries with limited resources for laboratory testing. The present study describes a series of 118 adult Thai patients with diffuse gliomas, classified by the WHO 2016 classification. The purpose was to demonstrate how a diagnosis can still be achieved using a simplified approach that combines clinical, morphological, immunohistochemical, and fewer molecular assays than typically performed. This algorithm starts with tumor location (midline vs. non-midline) with diffuse midline glioma identified by H3 K27M immunostaining. All other tumors are placed into one of 6 categories, based on morphologic features rather than specific diagnoses. Molecular testing is limited to IDH1/IDH2 mutations, plus co-deletion of 1p/19q for cases with oligodendroglial features and TERT promoter mutation for cases without such features. Additional testing for co-deletion of 1p/19q, TERT promoter mutation and BRAF mutations are only used in selected cases to refine diagnosis and prognosis. With this approach, we were able to reach the integrated diagnosis in 117/118 cases, saving 50 % of the costs of a more inclusive testing panel. The demographic data and tumor subtypes were found to be similar to series from other regions of the world. To the best of our knowledge, this is to the first reported series of diffuse gliomas in South-East Asia categorized by the WHO 2016 classification system.

Massive Perivillous Fibrin Deposition Associated With Placental Syphilis: A Case Report.

Massive perivillous fibrin deposition (MPFD) and the related entity of maternal floor infarction (MFI) are uncommon placental disorders of unknown etiology, associated with adverse obstetric outcome and a significant risk of recurrence. We describe a 19-year-old mother with untreated syphilis who delivered a male neonate with low birth weight, skin desquamation, and pneumonia. Placenta examination showed the expected changes for syphilis but unexpectedly, also showed MPFD. To our knowledge, this is the first report of MPFD associated with placental syphilis, thus expanding the list of etiologies that may be related to MPFD/MFI. It is postulated that the syphilis infection in our case led to a hypercoaguable state, eventually resulting in MPFD. In the right clinical setting, syphilis might be considered in the differential diagnosis when MPFD/MFI is observed on placental examination. The recurrence risk of MFPD/MFI associated with infections is believed to be lower than idiopathic cases and, by extrapolation, this lower risk should apply to syphilis as well.

Fusion of ALK to the melanophilin gene MLPH in pediatric Spitz nevi.

Spitzoid neoplasms typically affect young individuals and include Spitz nevus, atypical Spitz tumor, and Spitzoid melanoma. Spitz tumors can exhibit gene fusions involving the receptor tyrosine kinases NTRK1, NTRK3, ALK, ROS1, RET, or MET, or the serine-threonine kinase BRAF. Because most studies have been based on adult cases, we studied ALK fusions in Spitz nevi occurring in pediatric patients. Twenty-seven cases were screened for ALK expression by immunohistochemistry, and 6 positive cases were identified. These cases were studied further using the TruSight RNA Fusion Panel, and in 4 cases, exon 20 of the ALK gene was found to be fused to exon 14 of the MLPH (melanophilin) gene, a gene fusion that has only been reported in a Spitz nevus in an adult. The remaining 2 cases showed no fusion of ALK with any gene. The cases with the MLPH-ALK fusion showed a similar histology to that described for Spitz nevi with ALK fusions, with spindle-shaped and epithelioid melanocytes in fusiform nests with a plexiform growth pattern and infiltrative border. We created a breakapart fluorescence in situ hybridization assay for MLPH, and all 4 cases with the MLPH-ALK fusion were positive, whereas the other 23 cases in the study were negative. Thus, ALK and MLPH were fused only to each other in our series. Melanophilin is part of the melanosome trafficking apparatus together with MYO5a, TPM3, and RAB27a, all constitutively expressed in melanocytes. Kinase fusions involving MYO5A and TPM3 have been reported in Spitz tumors, and our series adds MLPH to this group.

Paediatric oral pathology in Thailand: a 15-year retrospective review from a medical teaching hospital.

OBJECTIVES: To determine whether the spectrum of oral pathology in children seen at a medical institution differs from studies derived from dental facilities. METHODS: Oral biopsy records from paediatric patients (<16 years of age) were retrieved from the pathology archives at Chulalongkorn University Hospital over a period of 15 years. Lesions were categorised as inflammatory/reactive, tumour/tumour-like or cystic. RESULTS: Two-hundred and thirty biopsies were identified. Most lesions were inflammatory/reactive (62%), followed by tumour/tumour-like (35%) and cystic (3%). The largest proportion of lesions was found in the 12-16 years' age group. Mucocele was the most common lesion (38%), followed by hemangioma (8.3%), irritation fibroma (6%) and nevus (6%). The predominance of mucocele is similar to that in reports from other countries. The proportion of malignant tumours (5%) was higher than in other studies (<1-2%). In contrast, odontogenic cysts and odontogenic tumours were rare (3% and <1%, respectively), compared with published studies (7-35% and 2-21%, respectively). CONCLUSIONS: This study from a medical institution shows a somewhat different spectrum of paediatric oral pathology compared with that reported from dental institutions. While some of the lesions may not be treated by dentists, they still need to be aware of these lesions because affected patients can still present initially to a dentist.

Pulmonary Neuroendocrine Cell Hyperplasia in Hemoglobin Bart-induced Hydrops Fetalis: A model for Chronic Intrauterine Hypoxia.

The pulmonary neuroendocrine system includes pulmonary neuroendocrine cells (PNECs) and neuroepithelial bodies (NEBs) that are distributed throughout respiratory epithelium and regulate lung growth and maturation antenatally. Abnormalities in this system have been linked to many hypoxia-associated pediatric pulmonary disorders. Hemoglobin (Hb) Bart disease is a severe form of α-thalassemia resulting in marked intrauterine hypoxia with hydrops fetalis (HF) and usually death in utero. Affected fetuses can serve as a naturally occurring human model for the effects of intrauterine hypoxia, and we postulated that these effects should include changes in the pulmonary neuroendocrine system. Bombesin immunostaining was used to assess PNECs and NEBs in stillborn fetuses with Hb Bart HF ( n = 16) and with HF from other causes ( n = 14) in comparison to non-HF controls. Hb Bart HF showed a significant increase in the proportion of PNECs in respiratory epithelium ( P = .002), mean number of NEB nuclei ( P = .03), and mean size of NEBs ( P = .002), compared to normal non-HF controls. Significant differences were not observed between HF due to other causes and non-HF controls with normal lungs. Non-HF controls with pulmonary hypoplasia showed significant increases in PNECs compared to HF cases not due to Hb Bart HF, implying HF alone does not cause such increases. In contrast, no significant differences were noted between non-HF controls with pulmonary hypoplasia and Hb Bart cases. Hb Bart HF may provide a useful model for studying the pulmonary neuroendocrine system under chronic intrauterine hypoxia.

BRAF V600E mutation in pediatric intracranial and cranial juvenile xanthogranuloma.

Juvenile xanthogranuloma (JXG) is a cutaneous form of non-Langerhans cell histiocytosis, primarily affecting children. The lesion is presumed to originate from either macrophages or dermal dendritic cells. JXG can rarely present as an isolated intracranial lesion and, in contrast to the dismal outcome of patients with systemic disease, cranial JXG has been shown to carry a more favorable prognosis. Here, we report for the first time 3 pediatric cases of JXG with a BRAF V600E mutation, 2 with intracranial lesions and 1 with cranial lesions. Although these intracranial/cranial lesions have been referred to as JXG, they likely differ from cutaneous JXG in both the clinical features and BRAF status. It may be more appropriate to classify intracranial/cranial JXG in the same group as Langerhans cell histiocytosis and Erdheim-Chester disease, which also have a BRAF V600E mutation. Further study of BRAF status in a larger series of JXG is warranted.

Cytokeratin-Negative Undifferentiated (Lymphoepithelial) Carcinoma of the Lacrimal Sac.

Epstein-Barr virus-associated undifferentiated (lymphoepithelial) carcinoma is a malignancy that most commonly arises in the nasopharynx but can also occur in other locations including the lacrimal sac. Generally, this tumor strongly expresses cytokeratin, making the diagnosis straightforward. In the absence of confirmatory immunohistochemistry, the diagnosis can be problematic, particularly for tumors arising in unusual locations. Only 3 cases arising in the lacrimal sac in association with Epstein-Barr virus have been reported in the English literature, and all showed typical pathologic findings. The authors report a fourth case, unique in that it showed negative immunostaining for all cytokeratins tested. The clue to the nature of the tumor came from identification of Epstein-Barr virus by in-situ hybridization and demonstration of tonofilaments by electron microscopy. This case demonstrates that a multimodal approach may be needed in the diagnosis of Epstein-Barr virus-associated carcinoma, especially when occurring in uncommon locations.

Dogs that develop rabies post-vaccination usually manifest the paralytic subtype.

Rabies infection can manifest as either encephalitic (furious) or paralytic (dumb) types, with a ratio of approximately 2:1 in dogs. The clinical type of rabies that develops post-vaccination has only been reported in studies from one country, all with similar findings. We report a study of 36 rabid dogs with obtainable vaccination history, presenting to The Queen Saovabha Memorial Institute, Bangkok, Thailand during 2002-2008. Dogs were classified into encephalitic or paralytic types. Of 22 non-vaccinated dogs, 16 (73%) had the encephalitic type. In contrast, of the 14 vaccinated dogs, 10 (71%) had the paralytic type, a difference that was significant (p=0.016). Recent studies on canine brains have shown that lymphocyte response is more pronounced in paralytic rabies at the brainstem level, whereas viral burden is greater in the encephalitic form. We postulate partial immune response in the vaccinated dogs might influence rabies to manifest as the paralytic type. These results can serve as a natural experiment that can help explain the basis for the differences between the paralytic and encephalitic forms of canine rabies.

TFE3-positive renal cell carcinomas are not always Xp11 translocation carcinomas: Report of a case with a TPM3-ALK translocation.

Translocation-associated renal cell carcinoma (RCC) is a distinct subtype of RCC with gene rearrangements of the TFE3 or TFEB loci. The TFE3 gene is located at Xp11 and can fuse to a number of translocation partners, resulting in high nuclear expression of TFE3 protein. TFE3 immunostaining is often used as a surrogate marker for a TFE3 translocation. We report a case of an RCC that expressed TFE3 but showed only gain of TFE3 rather than a translocation. Moreover, this case had a t(1;2) translocation fusing ALK and TMP3, identical to that seen in inflammatory myofibroblastic tumour. There was resulting overexpression of ALK protein in a cytoplasmic and membranous pattern. The patient was not treated with chemotherapy but following regional nodal recurrence, an ALK inhibitor was added and the patient remains alive one year later. There are only rare reports of RCC with an ALK-TMP3 fusion, and these tumours can express TFE3 on some unknown basis not related to a TFE3 translocation. Any RCC positive for TFE3 and lacking a translocation should be tested for ALK expression and translocation. Recognition of this subtype of RCC will allow ALK inhibitor therapy to be added, in the hope of improving patient outcome.