Carcinoma of unknown primary origin (CUP) involving the skeletal system is rare in dogs and may closely mimic primary bone neoplasia or multicentric lymphoma, creating substantial diagnostic challenges. A 15-year-old spayed female Jindo-mix dog was referred for rapidly progressive tetralimb lameness and inability to stand following a 2-week history of worsening forelimb lameness. Computed tomography revealed aggressive multifocal osteolytic and osteoproliferative lesions involving the pelvis, distal femur, and lumbar vertebra, accompanied by generalized lymphadenopathy, raising differential diagnoses including osteosarcoma, lymphoma, and metastatic neoplasia. Serial CT examinations demonstrated rapid progression of the dominant left ischial lesion, which was considered most consistent with a primary bone neoplasm and was surgically excised for definitive diagnosis. MRI failed to identify clinically significant neurologic disease. Histopathologic examination of a surgically excised ischial lesion favored poorly differentiated epithelial malignancy, although lymphoma could not initially be excluded. During hospitalization, serial thromboelastography (TEG) and coagulation testing demonstrated a predominantly hypercoagulable profile despite antithrombotic therapy. Following acute clinical deterioration, contrast-enhanced CT identified thrombosis involving the splenic vein and caudal vena cava, pulmonary thromboembolism (PTE), and concurrent multi-organ infarction. Cytology of an enlarged peripheral lymph node suggested metastatic carcinoma, and postmortem immunohistochemistry supported epithelial differentiation, and in the absence of an identifiable primary tumor despite comprehensive diagnostic evaluation, the case was clinically classified as carcinoma of unknown primary origin. This case highlights an unusual diagnostic presentation of skeletal CUP mimicking osteosarcoma or lymphoma and complicated by fatal cancer-associated thrombosis. Rapidly progressive multifocal bone lesions accompanied by hypercoagulability should prompt consideration of metastatic carcinoma, including carcinoma of unknown origin, even in the absence of an identifiable primary tumor.

Background/Objectives: Concern that COVID-19 vaccination causes pulmonary nodules persists because vaccination coincided with expanded computed tomography (CT), low-dose CT (LDCT) screening, post-COVID imaging and artificial intelligence (AI)-assisted detection. This review asks whether the current literature supports causality and how vaccination history should inform thoracic imaging. Methods: A focused search of PubMed, PubMed Central and the Cochrane Library was performed through 15 July 2026. Evidence was classified as direct or contextual; no PRISMA screening, risk-of-bias scoring or quantitative synthesis was performed. Results: Direct evidence remains sparse. One case report was too confounded for inference. A two-sample Mendelian randomization study found no broad lung disease risk signal, but nodules were not modeled and the heterogeneous endpoints were exploratory. An ecological study of 1,616,750 samples linked rising detection to SARS-CoV-2 infection waves and AI-assisted reading; lacking individual vaccination data, it cannot establish whether vaccination affected detection. Screening interruption produced the opposite pattern: Lung-RADS 4 nodules rose from 8% to 29%. The most reproducible post-vaccination thoracic finding is regional lymph-node activation on [18F]fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT), an expected immune response rather than a parenchymal nodule. Conclusions: Current evidence is insufficient to establish vaccination as an independent, population-level cause of pulmonary nodules. Vaccination history should guide [18F]FDG-PET/CT interpretation; CT-detected parenchymal nodules warrant standard risk stratification.

Cervical carcinosarcoma (CCS), also known as malignant mixed Müllerian tumor (MMMT) of the cervix, is an exceptionally rare and aggressive biphasic neoplasm composed of both epithelial and mesenchymal malignant components. Due to its rarity, optimal management strategies are not well established, particularly in low-resource settings. Most reported cases present at an advanced stage and are associated with poor prognosis. To our knowledge, this represents the first reported metastatic case of CCS from Sub-Saharan Africa. We report a case of advanced CCS in a 33-year-old woman who presented to a tertiary referral center in Northern Tanzania with a five-month history of heavy and prolonged vaginal bleeding, lower abdominal pain, headaches, palpitations, and generalized weakness. Clinical examination revealed a large vaginal mass with restricted uterine mobility and rectal involvement. Imaging demonstrated a heterogeneously enhancing cervical mass measuring 10 × 9 × 14 cm with parametrial invasion, recto-sigmoid infiltration, bilateral ovarian enlargement, peritoneal dissemination, lymphadenopathy, and ascites, consistent with FIGO stage IVB disease. Exploratory laparotomy revealed omental caking, bilateral ovarian masses, liver surface nodules, and extensive pelvic adhesions. A total abdominal hysterectomy (TAH) with bilateral salpingo-oophorectomy (BSO) was performed. Histopathological examination demonstrated a biphasic malignant tumor composed of carcinomatous elements arranged in nests and cords and sarcomatous pleomorphic spindle cells. Immunohistochemistry showed epithelial differentiation with p16 positivity and mesenchymal differentiation highlighted by desmin. Intraoperative findings and imaging confirmed ovarian and peritoneal metastases, consistent with advanced disease. Multidisciplinary review recommended systemic chemotherapy with carboplatin and paclitaxel followed by radiotherapy. Treatment was not initiated, however, due to financial constraints. The patient was subsequently lost to follow-up.

Papillary thyroid carcinoma (PTC) is an uncommon neoplasm in pediatric and transitional age groups, characterized by a biologically more aggressive local behavior than in adults. Although its coexistence with Hashimoto's thyroiditis (HT) is widely documented, the impact of this chronic inflammation on massive lymphatic dissemination remains a subject of debate. We present the case of a 17-year-old male who presented with cervical lymphadenopathy and computed tomography imaging suggestive of primary superior mediastinal involvement (prevascular and pretracheal). Initial fine-needle aspiration biopsy (FNAB) of the right cervical lymph node revealed atypical follicular cells with nuclear grooves, consistent with metastatic PTC. The patient underwent total thyroidectomy combined with modified bilateral radical neck dissection and central compartment neck dissection. Definitive histopathological examination confirmed a multifocal PTC (classic type and follicular variant) measuring 1.1 cm in its largest diameter, with lymphatic invasion on a background of HT (pathological staging pT1b pN1b pMx). Compartmental lymph node analysis revealed a massive metastatic burden, with 13 of 39 lymph nodes exhibiting bilateral involvement, highlighted by a 4.0 cm macrometastasis in the right middle jugular chain. Following surgery, adjuvant radioactive iodine (I-131) ablation therapy was administered after thyroid hormone withdrawal, and subsequent post-ablation follow-up laboratory testing confirmed severe endogenous hypothyroidism with a markedly elevated thyroid-stimulating hormone (TSH) level. This clinical case highlights the striking clinicopathological discrepancy that can exist between the small size of a primary thyroid tumor and the potential for disproportionate lymphovascular dissemination in the adolescent population. When encountering bulky mediastinal and cervical masses that mimic lymphomas, PTC must be considered a critical differential diagnosis, justifying comprehensive preoperative mapping and an aggressive compartmental surgical approach.

Background and Clinical Significance: Epstein-Barr virus (EBV) is a common infection that rarely causes acute pancreatitis. EBV-associated acute pancreatitis is an uncommon but potentially serious complication that may result from direct viral invasion of pancreatic tissue or immune-mediated inflammation. Because its presentation can overlap with other causes of acute pancreatitis, EBV may be overlooked when common aetiologies are not identified. Recognising EBV as a potential cause is important for accurate diagnosis and appropriate management, particularly in patients presenting with pancreatitis alongside features of acute EBV infection; Case Presentation: We report a case of 58-year-old female with EBV-induced acute pancreatitis. She had a flu like illness two weeks prior to hospital admission, tested positive for EBV IgM antibodies and received supportive treatment by her general practitioner. However, her condition deteriorated, leading to hospital admission. She developed epigastric pain and investigations showed elevated serum lipase, impaired liver function tests and acute kidney injury. CT abdomen showed hepatosplenomegaly, lymphadenopathy and peripancreatic oedema consistent with acute pancreatitis. She was initially treated with antibiotics, however; her condition worsened and she developed severe hypotension requiring intensive care admission. Aggressive fluid resuscitation, inotropic support and continuous veno-venous haemofiltration (CVVH) were required. She gradually improved and subsequently was stepped down to the medical ward for supportive care and rehabilitation. She made full recovery and was discharged home after a 6-week length of stay; Conclusions: EBV-associated acute pancreatitis is an uncommon but potentially severe complication of EBV infection. EBV should be considered in patients with acute pancreatitis when common aetiologies have been excluded, particularly when pancreatitis occurs alongside features of acute viral infection. Early recognition and appropriate supportive management may be important in preventing or limiting severe complications.

Background: Pleomorphic adenoma is the most common benign salivary-gland neoplasm and frequently affects the minor salivary glands of the palate. Although surgical excision is generally curative, incomplete encapsulation, pseudopod-like extensions, and microscopic tumor deposits may contribute to recurrence, which can occur many years after initial treatment. Recurrent palatal pleomorphic adenoma is uncommon and may present diagnostic and reconstructive challenges. Case Presentation: A 64-year-old man was referred with a painless, slowly enlarging recurrent mass of the right posterior hard palate, six years after excision of a pleomorphic adenoma at another institution. Magnetic resonance imaging and contrast-enhanced computed tomography demonstrated a well-defined enhancing palatal lesion measuring approximately 2.1 × 1.9 × 1.9 cm on MRI and 1.8 × 2.2 × 1.9 on CT, without adjacent maxillary bone destruction or cervical lymphadenopathy. An incisional biopsy was consistent with pleomorphic adenoma. Wide local excision was performed, including the tumor, surrounding palatal soft tissue, and underlying periosteum. The resulting defect was reconstructed using a facial artery musculomucosal flap. The postoperative course was uneventful, with satisfactory flap healing and preservation of speech and swallowing. At six months of follow-up, there was no clinical evidence of recurrence or functional impairment. Conclusions: Recurrent pleomorphic adenoma of the palate may develop several years after primary treatment. Complete surgical excision with tumor-free margins and appropriate reconstruction is essential. Long-term clinical follow-up is recommended because late recurrence and, rarely, malignant transformation may occur.

This study aims to present the diagnosis, treatment process, and clinical course of a patient with advanced rectal adenocarcinoma presenting with rare duodenal metastases. A 47-year-old male patient presented with constipation. A mass obstructing the entire lumen was detected in the rectosigmoid region, and the biopsy result was reported as rectal adenocarcinoma. Clinical staging was determined as T4aN2bM0. Due to the obstruction, a loop sigmoidostomy was performed, and Total Neoadjuvant Therapy (TNT) was planned. Within the scope of TNT, 5- Fluorouracil (5-FU), Oxaliplatin, Capecitabine, and 25 fractions of radiotherapy were administered. Surgically, Low Anterior Resection (LAR) was performed, and pathology confirmed pT4N2, with the presence of lymphovascular and perineural invasion. In the fifth postoperative month, preaortic and paraaortic lymphadenopathy was detected; a KRAS mutation was identified. Partial regression was observed in the lymph nodes following the new chemotherapy regimen (5-FU +Irinotecan+Bevacizumab), but cholestasis developed. Imaging and Endoscopic Retrograde Cholangiopancreatography (ERCP) revealed ulcerative metastatic masses in the duodenum and ampulla of Vater regions. Biopsy results and immunohistochemical analyses (CDX2, SATB2, Beta-Catenin) confirmed colon adenocarcinoma metastasis. Next-generation sequencing (NGS) analysis showed a recurrent KRAS mutation, stable microsatellite stability(MSI), and intact Mismatch Repair (MMR). Although symptomatic relief was achieved with biliary drainage and a duodenal stent, advanced metastases (liver, adrenal, bone) developed. Duodenal metastasis in patients with rectal adenocarcinoma is rare but clinically severe and has a poor prognosis. This case demonstrates the rare metastatic pathways of advanced colorectal cancer, management challenges, and palliative treatment strategies. Keywords: Rectal cancer; Duodenal metastasis; Intraluminal metastasis; KRAS mutation; Colorectal cancer.

Secondary syphilis is a clinical mimic with considerable morphological variability. We describe a man in his early 50s with a generalised papulosquamous eruption, constitutional symptoms and generalised lymphadenopathy, notably without palmoplantar involvement. Syphilis serology was strongly reactive, and histopathology demonstrated a plasma cell-rich superficial and deep perivascular and peri-adnexal infiltrate. This case illustrates the importance of considering secondary syphilis in generalised papulosquamous eruptions despite the absence of classical palmoplantar lesions.

Background/objective: Kawasaki disease is an acute, systemic vasculitis most commonly observed in young Asian children. While the exact pathogenesis remains unknown, it is thought to be triggered by a pathogenic exposure that elicits an inflammatory response several days to 2 weeks before the onset of symptoms. Symptoms include edematous hands and feet, conjunctivitis, mucositis, a diffuse erythematous rash, lymphadenopathy, and a fever lasting for at least 5 days, which is required for diagnosis. In addition, coronary vessels may exhibit aneurysms, thrombosis, and stenosis. Without treatment, Kawasaki disease carries a 25% risk of developing coronary aneurysms. However, with the timely administration of intravenous immunoglobulin, this risk is reduced to 4%. Given the inflammation and possible thrombosis of the coronary vasculature, current guidelines recommend aspirin for the management of Kawasaki disease. Kawasaki disease is one of the few conditions in which administering aspirin to children is considered acceptable, despite the risk of inducing Reye syndrome, a potentially fatal condition triggered by a viral infection while taking salicylates such as aspirin. Therefore, this review addresses a key question: why continue to use aspirin with its known risk of Reye syndrome when alternative antithrombotic drugs used in pediatric patients are available? This review seeks to explore potential substitutes for aspirin to mitigate the risk of Reye syndrome while also providing the necessary anticoagulation in Kawasaki disease.

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms of the gastrointestinal tract. They most often arise in the stomach, followed by the small intestine. Small bowel GISTs usually present with gastrointestinal bleeding, anemia, abdominal pain, or nonspecific symptoms, whereas intestinal obstruction is uncommon because these tumors typically grow outward from the bowel wall. We report the case of a 58-year-old woman with no previous abdominal surgery who presented with one month of abdominal pain, constipation, and vomiting, which progressed to complete absence of stool and flatus for 48 hours. CT and MRI showed a 4.5-cm exophytic distal ileal mass with multiple peritoneal nodules and no liver lesions or lymphadenopathy. Because of the obstructive presentation, exploratory laparoscopy was performed. Intraoperative findings showed a stenosing ileal tumor and diffuse peritoneal implants. Frozen-section analysis of two nodules suggested metastatic GIST, and segmental ileal resection with primary anastomosis was performed to relieve the obstruction and establish a definitive diagnosis. Histology showed a spindle-cell GIST positive for KIT (CD117) and DOG1, with a mitotic rate of 4/50 high-power fields. The peritoneal nodules were metastatic implants. The postoperative course was uneventful, and imatinib 400 mg daily was started one week later. After nearly two years of clinical and radiological follow-up, the patient remained stable without disease progression. This report highlights that ileal GIST should be considered in cases of unexplained small bowel obstruction, especially when imaging shows an exophytic mass without lymphadenopathy.