A novel Imidazo[1,2-a]pyridine derivative modulates active KRASG12D through off-like conformational shifts in switch-I and switch-II regions, mimicking inactive KRASG12D.

KRASG12D are the most prevalent oncogenic mutations and a promising target for solid tumor therapies. However, its inhibition exhibits tremendous challenge due to the necessity of high binding affinity to obviate the need for covalent binders. Here we report the evidence of a novel class of Imidazo[1,2-a]pyridine derivative as potentially significant novel inhibitors of KRASG12D, discovered through extensive ligand-based screening against 2-[(2R)-piperidin-2-yl]-1H-indole, an important scaffold for KRASG12D inhibition via switch-I/II (S-I/II) pocket. The proposed compounds exhibited similar binding affinities and overlapped pose configurations to 2-[(2R)-piperidin-2-yl]-1H-indole, serving as a reliable starting point for drug discovery. Comparative free energy profiles demonstrated that C4 [2-methyl-3-((5-phenyl-1H-1,2,4-triazol-3-yl)methyl)imidazo[1,2-a]pyridine] effectively shifted the protein to a stable low-energy conformation via a prominent transition state. The conformational changes across the transition revealed the conformational shift of switch-I and II to a previously known off-like conformation of inactive KRASG12D with rmsd of 0.91 Å. These conformations were even more prominent than the privileged scaffold 2-[(2R)-piperidin-2-yl]-1H-indole. The representative structure overlay of C4 and another X-ray crystallography solved BI-2852 bound inactive KRASG12D revealed that Switch-I and II exhibited off-like conformations. The cumulative variance across the first eigenvalue that accounted for 57 % of the collective variance validated this on-to-off transition. In addition, the relative interaction of C4 binding showed consistent patterns with BI-2852. Taken together, our results support the inhibitory activity of [2-methyl-3-((5-phenyl-1H-1,2,4-triazol-3-yl)methyl)imidazo[1,2-a]pyridine] by shifting active KRASG12D to an inactive conformation.

Diagnostic Dilemma: IgG4-Related Sclerosing Mesenteritis Mimicking an Abdominal Malignancy Enveloping the Superior Mesenteric Artery.

Sclerosing mesenteritis, a rare fibroinflammatory disease affecting the mesentery, presents a diagnostic challenge due to its varied clinical manifestations and unknown etiology. We present a case of a 50-year-old female presenting with epigastric pain and weight loss, initially suspected of abdominal malignancy. Imaging revealed a mesenteric mass, and histopathological examination confirmed dense lymphoplasmacytic infiltrate with storiform fibrosis, along with elevated serum IgG4 levels, indicative of IgG4-related sclerosing mesenteritis. Treatment with thalidomide and prednisolone resulted in significant mass regression and symptom improvement. Our case highlights the importance of considering sclerosing mesenteritis in the differential diagnosis of abdominal masses and suggests a potential therapeutic approach for this rare condition. Further research is warranted to elucidate its pathogenesis and optimize management strategies.

Fine needle aspiration diagnosis of benign oncocytic lesions of the head and neck associated with false positive 18F-fluorodeoxyglucose uptake on positron emission tomography scan.

INTRODUCTION: 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) has become the mainstay for staging and post-therapy surveillance of cancer as malignant neoplasms generally demonstrate higher FDG uptake that benign entities. However, there are certain benign lesions, most notably oncocytic tumors, that can display very high uptake and fine needle aspiration (FNA) is usually done to confirm malignancy. Therefore, it is important to recognize that benign oncocytic lesions of the head and neck may also present as FDG-avid lesions to avoid a diagnostic pitfall. METHODS: Electronic search of institutional surgical and cytopathology archives was conducted to identify cases of benign oncocytic lesions involving the head and neck region diagnosed by FNA from January 2012 to April 2022. Chart review was used to assess whether lesions were initially discovered via PET scanning. RESULTS: One hundred and twenty-five cases of oncocytic lesions were identified; 12 (9%) PET positive lesions were identified in the head and neck region from patients being evaluated for metastasis or for suspicion of malignancy. Cytopathology of all 12 cases demonstrated benign oncocytic lesions; eight (67%) of these cases were consistent with Warthin tumor, one (8.3%) was a benign oncocytic lesion, and one (8.3%) was consistent wit a parathyroid adenoma. Most (58%) of the PET-positive lesions were in parotid region, two from thyroid gland (17%), one from submandibular gland (8%), one from paratracheal area (8%). The PET scan SUVs ranged from 3.3 to 19.5 g mL-1. CONCLUSIONS: Oncocytic lesions including Warthin tumors can result in false-positive FDG uptake on PET scans. Clinicians and cytopathologists should be aware of PET-positive benign oncocytic head and neck lesions.

Anaplastic Large Cell Lymphoma of the Spine: Report of a Rare Case.

This abstract discusses a rare case of anaplastic large cell lymphoma (ALCL) involving the cervical and dorsal spine in a 17-year-old female. ALCL is a distinct subtype of lymphoma characterized by abnormal proliferation of lymphocytes and is divided into ALK-positive and ALK-negative subtypes. Spinal involvement in ALCL is uncommon, particularly in the cervical and dorsal regions. The patient presented with persistent fever, weakness, and delayed onset of severe neck pain. Diagnosis involved imaging, bone marrow biopsy, and lymph node biopsy. Treatment strategies for ALCL typically involve a multimodal approach, including chemotherapy, radiotherapy, and targeted therapy. However, due to the rarity of spinal involvement, treatment decisions are based on extrapolation from other ALCL cases. Prognosis is influenced by disease stage and ALK status, but specific outcomes for spinal involvement remain poorly established. This case emphasizes the need for considering lymphoma in patients with unexplained symptoms and abnormal imaging findings. It highlights the importance of further research to improve the understanding and management of ALCL with spinal involvement.

A Symphony of Challenges: Multi-Drug Resistant Tuberculosis, Pleurocutaneous Fistula, and Empyema Necessitans in Concert.

This case report details the clinical course of a 37-year-old male with multi-drug-resistant tuberculosis (MDR-TB) who initially presented with respiratory symptoms. Following a month of anti-TB therapy, the patient developed a painful chest swelling, diagnosed as empyema necessitans, with a subsequent spontaneous rupture leading to a pleurocutaneous fistula. Despite recommendations for surgery, the patient opted for active surveillance. The follow-up revealed symptom improvement. This case underscores the unique challenges of managing rare complications of MDR-TB, particularly when patients decline surgical interventions. The observed symptom improvement, despite the absence of surgery, illuminates the intricate decision-making process and alternative management strategies involved in addressing such complications, highlighting the complexities inherent in MDR-TB care.

Association of IL-17F rs2397084 (E126G), rs11465553 (V155I) and rs763780 (H161R) variants with rheumatoid arthritis and their effects on the stability of protein.

Interleukin-17F (IL-17F), considered a pro-inflammatory cytokine, has been shown to contribute to skeletal tissue degradation and hence chronic inflammation in rheumatoid arthritis (RA). In this study we utilized bioinformatics tools to analyze the effect of three exonic SNPs (rs2397084, rs11465553, and rs763780) on the structure and function of the IL-17F gene, and evaluated their association with RA in Pakistani patients. The predicted deleterious and damaging effects of identified genetic variants were assessed through the utilization of multiple bioinformatics tools including PROVEAN, SNP&GO, SIFT, and PolyPhen2. Structural and functional effects of these variants on protein structures were evaluated through the use of additional tools such as I-Mutant, MutPred, and ConSurf. Three-dimensional (3D) models of both the wild-type and mutant proteins were constructed through the utilization of I-TASSER software, with subsequent structural comparisons between the models conducted through the use of the TM-align score. A total of 500 individuals, 250 cases and 250 controls, were genotyped through Tri-ARMS-PCR method and the resultant data was statistically analyzed using various inheritance models. Our bioinformatics analysis showed significant structural differences for wild type and mutant protein (TM-scores and RMSD values were 0.85934 and 2.34 for rs2397084 (E126G), 0.87388 and 2.49 for rs11465553 (V155I), and 0.86572 and 0.86572 for rs763780 (H161R) with decrease stability for the later. Overall, these tools enabled us to predict that these variants are crucial in causing disease phenotypes. We further tested each of these single nucleotide variants for their association with RA. Our analysis revealed a strong positive association between the genetic variant rs763780 and the risk of developing rheumatoid arthritis (RA) at both the genotypic and allelic levels. The genotypic association was statistically significant[χ2 = 111.8; P value <0.0001], as was the allelic level [OR 3.444 (2.539-4.672); P value 0.0008]. These findings suggest that the presence of this genetic variant may increase the susceptibility to RA. Similarly, we observed a significant distribution of the genetic variant rs11465553 at the genotypic level [χ2 = 25.24; P value = 0.0001]. However, this variant did not show a significant association with RA at the allelic level [OR = 1.194 (0.930-1.531); P value = 0.183]. However, the distribution of variant rs2397084 was more or less random across our sample with no significant association either at genotypic and or allelic level. Put together, our association study and in silico prediction of decreasing of IL17-F protein stabilty confirmed that two SNPs, rs11465553 and rs763780 are crucial to the suscetibility of and showed that these RA in Pakistani patients.

Delayed intestinal obstruction from an unintentionally retained surgical gauze in a 24-year old woman two years after caesarean section: a case report.

BACKGROUND: One of the most common surgical emergencies, intestinal obstruction is rarely the result of an inadvertently retained foreign object (also known as a gossypiboma), which may not present symptoms for a lifetime. It also carries additional legal burdens, which may account for the rarity of its reports. CASE PRESENTATION: We report a 24-year-old Sudanese female with a history of emergency Caesarean section two years before the admission presented with abdominal distension and absolute constipation, which was diagnosed as intestinal obstruction with a retained gauzed found within the small intestine. Moreover, a review of recent African-reported cases was done to find relatively similar cases. CONCLUSION: Adhering to the standard of care in surgical theaters and integrating new methods of prevention like tagged gauze could help to decrease the rate of such cases in the future.

Flow cytometry improves the diagnostic value of fine needle aspiration cytology in a spleen with neuroendocrine tumor: A case report.

Fine needle aspirations are infrequently performed on the spleen due to concerns for hemorrhagic complications. As a result, splenic lesions can be challenging to diagnose given the limited amount of available specimen. Metastasis to the spleen is rare and metastatic neuroendocrine tumors to the spleen are scarce in literature. The diagnosis of splenic lesions from fine needle aspirate entails processing which prolongs the turnaround time, particularly if the cytomorphology is non-typical and a limited sample can further complicate this process. We describe a case in which flow cytometry performed on fine needle aspiration of a splenic lesion suggested a diagnosis of neuroendocrine neoplasm involving the spleen. Further workup confirmed this diagnosis. Flow cytometry can recognize neuroendocrine tumors involving the spleen in a timely manner so that appropriate immunohistochemistry tests on limited specimens can be performed to aid in their accurate diagnosis.

Identification of novel peptide inhibitors for the KRas-G12C variant to prevent oncogenic signaling.

Kirsten rat sarcoma viral oncogene homolog (KRas) activating mutations are common in solid tumors, accounting for 90%, 45%, and 35% of pancreatic, colorectal, and lung cancers (LC), respectively. Each year, nearly 150k new cases (both men and women) of KRas-mutated malignancies are reported in the United States. NSCLC (non-small cell lung cancer) accounts for 80% of all LC cases. KRas mutations are found in 15% to 25% of NSCLC patients. The main cause of NSCLC is the KRas-G12C mutation. The drugs Sotorasib and Adagrasib were recently developed to treat advanced NSCLC caused by the KRas-G12C mutation. Most patients do not respond to KRas-G12C inhibitors due to cellular, molecular, and genetic resistance. Because of their safety, efficacy, and selectivity, peptide inhibitors have the potential to treat newly developing KRas mutations. Based on the KRas mutations, peptide inhibitors that are highly selective and specific to individual lung cancers can be rationally designed. The current study uses an alanine and residue scanning approach to design peptide inhibitors for KRas-G12C based on the known peptide. Our findings show that substitution of F3K, G11T, L8C, T14C, K13D, G11S, and G11P considerably enhances the binding affinity of the novel peptides, whereas F3K, G11T, L8C, and T14C peptides have higher stability and favorable binding to the altered peptides. Overall, our study paves the road for the development of potential therapeutic peptidomimetics that target the KRas-G12C complex and may inhibit the KRas and SOS complex from interacting.Communicated by Ramaswamy H. Sarma.

Computational screening and analysis of deleterious nsSNPs in human p14ARF (CDKN2A gene) protein using molecular dynamic simulation approach.

Cyclin-dependent kinase inhibitor 2 A (CDKN2A) gene belongs to the cyclin-dependent kinase family that code for two transcripts (p16INK4A and p14ARF), both work as tumor suppressors proteins. The mutation that occurs in the p14ARF protein can lead to different types of cancers. Single nucleotide polymorphisms (SNPs) are an important type of genetic alteration that can lead to different types of diseases. In this study, we applied the computational strategy on human p14ARF protein to identify the potential deleterious nsSNPs and check their impact on the structure, function, and protein stability. We applied more than ten prediction tools to screen the retrieved 288 nsSNPs, consequently extracting four deleterious nsSNPs i.e., rs139725688 (R10G), rs139725688 (R21W), rs374360796 (F23L) and rs747717236 (L124R). Homology modeling, conservation and conformational analysis of mutant models were performed to examine the divergence of these variants from the native p14ARF structure. All-atom molecular dynamics simulation revealed a significant impact of these mutations on protein stability, compactness, globularity, solvent accessibility and secondary structure elements. Protein-protein interactions indicated that p14ARF operates as a hub linking clusters of different proteins and that changes in p14ARF may result in the disassociation of numerous signal cascades. Our current study is the first survey of computational analysis on p14ARF protein that determines the association of these nsSNPs with the altered function of p14ARF protein and leads to the development of various types of cancers. This research proposes the described functional SNPs as possible targets for proteomic investigations, diagnostic procedures, and treatments.Communicated by Ramaswamy H. Sarma.

Sonographic Characteristics and Pathology Correlation of Breast Imaging Reporting and Data System (BI-RADS) Category 4 Lesions.

INTRODUCTION: The Breast Imaging-Reporting and Database System (BI-RADS) category 4 is designated for breast lumps that do not display the typical features of malignancy but still raise enough suspicion to warrant a recommendation for a biopsy, as malignancy cannot be ruled out through imaging alone. The main objective of this study was to investigate the sonographic characteristics and pathology correlation of BI-RADS 4 breast lesions and determine the positive predictive rate of BI-RADS 4 lesions in diagnosing breast cancer, using histopathology as the gold standard. METHODS: This was a cross-sectional study conducted at the Department of Radiology, Aga Khan University Hospital in Karachi, spanning from May 2021 to August 2022, with a duration of 15 months. The study focused on female patients over the age of 18 who presented with suspicious breast lesions on ultrasound. Both mammography and ultrasound-guided core needle biopsy were performed on these patients, followed by a detailed histopathological evaluation of the biopsy specimens. To calculate the positive predictive value (PPV), true positive cases were identified through both histopathology and ultrasonography. RESULTS: A total of 227 cases were categorized as BI-RADS 4 lesions, with the patients' mean age being 47.8 ± 14.3 years (range: 17 - 88). Among the biopsied lesions, 101 cases were confirmed to be true positive for breast malignancies, resulting in a PPV for malignancy of 44.9%. Conversely, there were 124 false positive cases out of the 227 BI-RADS 4 category lesions (54.63%). The primary indication for presentation was a breast lump, and out of the 101 confirmed malignant cases, 70 (69.3%) were associated with malignancy. CONCLUSION: BI-RADS 4 can be utilized to assess suspicious breast lumps; however, for more reliable results and to avoid false negatives, histopathological confirmation should complement the imaging findings.

A Race Against Time: Early-Onset Differentiation Syndrome Following All-Trans-Retinoic-Acid (ATRA) Therapy in Acute Promyelocytic Leukemia (AML-M3).

This study reports a case of differentiation syndrome, a rare complication of ATRA (all-trans-retinoic-acid) therapy, observed in a 20-year-old male with acute promyelocytic leukemia (APML). Following the initiation of ATRA therapy for APML, the patient presented with fever, bleeding gums, bloody stool, and mouth ulcers. After 36 hours, he developed respiratory distress, hypotension, tachycardia, and hypoxemia, leading to the diagnosis of differentiation syndrome. ATRA therapy was promptly discontinued, and the patient, exhibiting type 1 respiratory failure, necessitated intubation. The management included hydroxyurea, dexamethasone, vasopressors, intravenous fluids, and furosemide. After seven days, significant improvement was observed, underscoring the importance of recognizing and promptly addressing differentiation syndrome in APML patients undergoing ATRA therapy. This case emphasizes the necessity of ATRA discontinuation, coupled with the judicious use of steroids and hydroxyurea, in the effective management of differentiation syndrome.

Association study of CCR6 rs3093024 with Rheumatoid Arthritis in a Pakistani cohort.

C-C Chemokine receptor 6 (CCR6), an important protein in inflammatory and immunological responses, has been previously reported to be associated with rheumatoid arthritis (RA). Therefore, in order to replicate these findings, a case-control study was conducted on 500 subjects (including 250 RA patients and 250 healthy controls) of Pakistani origin. The aim of this study was to determine the association of CCR6 rs3093024 variant with RA and identify its role in splicing events using bioinformatics tools. The clinical and demographic characteristics of the patients were collected using a well-designed questionnaire. The genotype frequencies of CCR6 rs3093024 variant were determined using tetra-primer ARMS-PCR (amplification of refractory mutation system-polymerase chain reaction) method. A significant difference was found between CCR6 rs3093024 genotype frequencies [P = 0.0016, χ 2  = 12.915]. Similarly, a significant difference in the allele frequencies between RA patients and healthy controls was also observed [P = 0.0003 and OR (95% CI) = 0.63 (0.49-0.80)]. The stratification of patients showed that there was a significant increase in AA genotype against AG + GG in patients [P = 0.0014, OR (95% CI) = 2.0 (1.32-3.02)]. Furthermore, using bioinformatics analysis, it was found that CCR6 rs3093024 variant might create a potential splicing enhancer motif (SF2/ASF (IgM-BRCA1) with score of 77.92; Threshold 70.53), which might have important impact on the product of this gene. This study suggests that the A variant of CCR6 rs3093024 variant is significantly associated with RA-risk and its G variant is protective in Pakistani population but a multi-cohort large sized population study is needed to elucidate these results. Moreover, functional studies are needed to highlight the effects of this polymorphism on the function of CCR6 gene.

A 35-Year-Old Woman With Progressive Dyspnea and Cough.

CASE PRESENTATION: A 35-year-old woman with no known medical history presented to the ED with complaints of progressive dyspnea for several months. The patient also reported episodic cough with yellow to green sputum production. She denied fever, chills, weight loss, or hemoptysis. She also denied any history of previous lung diseases in her family. She denied any history of tobacco or recreational drug use or any exposures. She was originally from El Salvador and immigrated to the United States approximately 3 years earlier. She was evaluated in El Salvador at age 15 for "lung issues" but had never received a formal diagnosis.

Morphoproteomics Identifies the Foamy Alveolar Macrophage as an M2 Phenotype with PD-L1 Expression in the Early Lesion of Post-Primary Tuberculosis: Implications for Host Immune Surveillance and Therapy.

Post-primary tuberculosis (TB) disease is characterized by paucibacillary necrosis of the early lesion, tuberculous pneumonia, in the adult human lung. The mechanism is speculated to be a strong localized delayed type hypersensitive response (DTH). However, up to this date, no one has been able to identify the source of the large accumulation of MTB antigens required for the DTH response. Although it is known and accepted that the pathogen, Mycobacterium tuberculosis (MTB), significantly affects macrophage function and activity, few studies have focused on macrophages at the site of the early lesion of developing post-primary MTB in human lungs. In vitro studies have examined the effect of MTB on skewing the macrophage phenotype, specifically the dynamic of the M1 and M2 differentiation. Additionally, it is also well documented that MTB infection induces macrophages to become foamy, accumulating host, and potentially MTB, lipids in the cytoplasm. The foamy macrophage is necessary for prolonging MTB survival in the infected lung. Using autopsy derived lung samples from untreated TB diseased individuals, this report, by applying morphoproteomics, demonstrates that the alveolar macrophages present in the early lesion of TB are primarily of the M2 phenotype. The M2 foamy alveolar macrophages (FAM) are also loaded with MTB antigens by immunohistochemistry and are paucibacillary. Moreover, the M2 alveolar macrophages predominately express PD-L1, leading to suppression of PD-1+ lymphocytes and host immunosurveillance. These morphoproteomic analyses indicate that early lesion of MTB in the adult human lung leads to a skewed M2 foamy alveolar macrophage phenotype that creates a protective microenvironment that accumulates high concentrations of MTB antigens, which when released can lead to necrosis and eventual cavitation.

Morphoproteomics Identifies CXCR4 in Undifferentiated Colorectal Cancer: A Case Study with Therapeutic Implications.

Undifferentiated colorectal cancer (UCRC) has a well-documented CD44 cancer stem cell (CSC) component. CXCR4 (C-X-C motif receptor 4) also is a CSC marker and with its ligand, stromal-derived factor (SDF)-1 alpha has been shown to act in concert with CD44 to promote cancer cell invasion. To date, CXCR4 has not been reported in the MEDLINE (PubMed) literature with respect to UCRC. Morphoproteomic analysis, utilizing bright field microscopy, can visualize the intensity and cell location of protein analytes with a patient's tumor including CXCR4 expression and was applicable to this case study. Using morphoproteomic analysis we identified chromogenic expression of both CD44 on the plasmalemmal aspect of the majority of the undifferentiated colorectal cancer foci and CXCR4 expression on the plasmalemmal or cytoplasmic aspect in up to 50% of the tumor cells in some regions and also on the intratumoral endothelial cells in the patient's UCRC. Moreover, both CSC markers were retained in the foci showing incomplete mucinous differentiation. In the context of data mining of the scientific literature, these findings suggest a collaboration between CXCR4 and CD44 in promoting tumor invasion and angiodependent metastasis in UCRC. Therapies designed to inhibit both the CD44 and the CXCR4 pathways are available and could reduce the metastatic potential of UCRC.

Pleomorphic Invasive Lobular Carcinoma of the Male Breast: Two Case Reports with Opposite Hormone Receptor Status.

Male breast cancer represents <1% of breast cancers, with invasive lobular carcinoma in male breast being extremely rare. Only four cases of male breast with pleomorphic lobular carcinoma (PLC) are reported in literature. Here, we report two additional cases. The first case was a 63-year old male presenting with a left neck mass, progressive facial numbness, bilateral cervical lymphadenopathy, and brain metastasis. Neck mass and left breast biopsies confirmed left breast PLC with metastasis. The second case was a 79-year old male with a left breast mass; biopsy and subsequent mastectomy showed PLC. Awareness of this entity is important for rendering an accurate diagnosis, especially in the setting of metastases.

Tumor-Infiltrating Lymphocyte Volume Is a Better Predictor of Disease-Free Survival Than Stromal Tumor-Infiltrating Lymphocytes in Invasive Breast Carcinoma.

OBJECTIVES: Tumor-infiltrating lymphocytes (TILs) have recently emerged as a prognostic factor in breast cancer. In our previous study, we proposed that tumor stroma should also be considered in the calculation of TILs and we introduced tumor infiltration lymphocyte volume (TILV) in triple-negative breast cancer. METHODS: We assessed the disease-free survival predictive value of TILV in all subtypes of invasive breast carcinoma and compared the predictive value of TILV with TILs. Differences between disease-free survival curves were determined by using the log-rank test, and Kaplan-Meier survival plots were generated for both groups. RESULTS: TILV was significantly correlated with disease-free survival in both invasive ductal carcinoma (P = .03) and all subtypes of invasive breast carcinoma (P = .043), whereas TILs failed to show a statistical significance. CONCLUSIONS: Tumor-stroma ratio needs to be considered in estimation of tumor immunity, and TILV adds more predictive power to TILs.

A rare presentation of carcinosarcoma of the bone in a young female; response with gemcitabine and docetaxel.

BACKGROUND: Sarcomatoid carcinoma, or carcinosarcoma, is a neoplasm that contains both sarcomatous and carcinomatous elements. It is an extremely rare cancer most often arising from visceral organs. Here we report the seventh documented de novo case of carcinosarcoma of the bone, in a young female who showed initial clinical improvement with gemcitabine and docetaxel. CASE PRESENTATION: A 36-year-old Caucasian female presented with diffuse musculoskeletal pain that had progressed from her shoulder to her back, arm, and knee over 6 months. Imaging revealed diffuse sclerotic lesions of bilateral humeral heads, iliac and ischial bones, and thoracic and lumbar spine. Histopathologic examination of biopsies from the T9 vertebra and left femur showed mainly sarcomatous spindle cells with focal osteoid production. Immunostaining showed the cells to be OSCAR cytokeratin, patchy positive for pankeratin, and negative for CK7, GATA3, S100, SOX10, CD99, EMA, AE1/AE3, and HMW keratin indicative of an epithelial origin. After thorough clinical correlation, sarcomatoid carcinoma of a visceral organ was excluded and the diagnosis of primary sarcomatoid carcinoma of the bone was ultimately favored. She received chemotherapy with gemcitabine and docetaxel, and showed improvement at 6 months but ultimately passed 1 year post diagnosis. CONCLUSIONS: Primary carcinosarcoma of the bone is an extremely rare malignancy. Early diagnosis is crucial as localized disease may be curable with resection. As shown in this case, combination chemotherapy with gemcitabine and docetaxel is a potential option in patients with unresectable or metastatic disease.

Cat-Scratch Disease in an AIDS Patient Presenting with Generalized Lymphadenopathy: An Unusual Presentation with Delayed Diagnosis.

BACKGROUND Bartonella infection is the causative organism of cat-scratch disease (CSD), which typically presents with self-limited localized lymphadenopathy. In HIV-infected patients, Bartonella infection can cause systemic illnesses with significant morbidity and mortality manifesting as bacillary angiomatosis (BA), hepatic peliosis, splenitis, bacteremic febrile illness, and other organ involvement. To the best of our knowledge, there have been no reports of HIV-infected patients presenting with generalized lymphadenopathy caused by Bartonella infection. We report an unusual case of CSD presenting with generalized lymphadenopathy in an AIDS patient with advanced immunosuppression. CASE REPORT A 44-year-old woman with AIDS, advanced immunosuppression, and intermittent adherence to antiretroviral therapy and medical care, presented with cough and increased generalized tender lymphadenopathy. A lymph node biopsy 1 year earlier was non-diagnostic for tuberculosis, fungal infection, and lymphoproliferative disorders. She remained with generalized lymphadenopathy. A repeat biopsy with the addition of Warthin-Starry silver staining suggested the diagnosis of cat-scratch lymphadenitis. She responded well to a long course of azithromycin antibiotic therapy, with the resolution of lymphadenopathy. CONCLUSIONS Cat-scratch disease may present with prolonged generalized lymphadenopathy, an unusual presentation in HIV patients with advanced immunosuppression. Awareness of the possibility of CSD in a similar clinical scenario may prompt early recognition and management of this disease.