Tuberculous endocarditis is a rare manifestation of Mycobacterium tuberculosis and may present as blood culture-negative infective endocarditis (BCNE). A 34-year-old male with no prior documented immunosuppressive illness or comorbidities, resident of Raisen district, Madhya Pradesh - a high tuberculosis (TB)-burden region - presented with a three-month history of intermittent high-grade fever, night sweats, and significant weight loss. Examination revealed pallor and tender cervical lymphadenopathy. Laboratory evaluation showed anaemia, leukopenia (WBC 2.85 × 10³/μL), elevated ferritin (640.60 ng/mL), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), while repeated pre-treatment blood and urine cultures were sterile. Chest radiograph revealed bilateral hilar lymphadenopathy. Echocardiography, performed in the context of a newly auscultated tricuspid regurgitation murmur and persistent fever despite broad-spectrum antibiotics, demonstrated flail tricuspid valve leaflets with vegetations consistent with infective endocarditis. Bone marrow biopsy showed epithelioid granulomas with Langhans-type giant cells. Contrast-enhanced computed tomography (CECT) of the thorax and abdomen revealed necrotic mediastinal lymphadenopathy, hepatic granulomas, abdominal (periportal and paraaortic) lymphadenopathy, and pulmonary tree-in-bud nodules. The spleen was unremarkable. Bronchoalveolar lavage cartridge-based nucleic acid amplification test (CBNAAT) detected rifampicin-sensitive M. tuberculosis, confirming disseminated TB. A diagnosis of disseminated TB with presumptive tricuspid valve endocarditis was made. The patient responded rapidly to first-line antituberculous therapy (HRZE (isoniazid, rifampin, pyrazinamide, and ethambutol) × two months, followed by HR (isoniazid and rifampin) × 10 months; total 12 months) with adjunctive corticosteroids, becoming afebrile within a week. We report this case to highlight M. tuberculosis as a rare but important aetiology of culture-negative endocarditis, particularly in patients from TB-endemic regions, and to illustrate the clinical reasoning required when valve tissue cannot be obtained for confirmation.

Sarcoidosis is a multisystem granulomatous disorder that most commonly involves the lungs and intrathoracic lymph nodes. Hypercalcemia is a recognized but uncommon manifestation of sarcoidosis and is typically mild; however, severe hypercalcemia as the initial presentation is rare and may pose a diagnostic challenge. We report a 66-year-old female patient with multiple comorbidities, including stage 4 chronic kidney disease, who presented with fatigue, decreased appetite, vomiting, and significant weight loss. Laboratory findings demonstrated severe hypercalcemia (15.7 mg/dL) with acute worsening of renal function. Parathyroid hormone (PTH) levels were inappropriately normal in this setting. Neck ultrasonography suggested a possible parathyroid lesion; however, technetium-99m sestamibi scintigraphy showed no focal uptake, excluding a functional adenoma. Further workup excluded malignancy and vitamin D intoxication. Elevated 1,25-dihydroxyvitamin D levels suggested extrarenal activation. Positron emission tomography-computed tomography (PET/CT) revealed widespread lymphadenopathy, and mediastinal lymph node biopsy confirmed noncaseating granulomas, establishing the diagnosis of sarcoidosis. The patient developed refractory hypercalcemia requiring aggressive medical therapy, denosumab, and one session of hemodialysis. Initiation of corticosteroid therapy resulted in rapid clinical and biochemical improvement. This case highlights severe vitamin D-mediated hypercalcemia as an uncommon presentation of sarcoidosis with acute kidney injury. Cases requiring both denosumab and hemodialysis are rarely reported. A systematic approach to evaluation is essential, particularly in distinguishing PTH-dependent from independent causes. Sarcoidosis should be considered in unexplained severe hypercalcemia, even in the absence of pulmonary manifestations, as early recognition and corticosteroid therapy can be highly effective.

Rosai-Dorfman disease (RDD) is a rare, clinically heterogeneous, multisystem, non-Langerhans cell histiocytosis. The discovery of recurrent and somatic mutations in the MAPK signaling pathway in a subset of these patients, starting in 2016, subsequently led to a reclassification of RDD from an inflammatory disorder to a neoplastic process. It is now included in the revised 2022 World Health Organization classification of hematolymphoid tumors. The hallmark of RDD is massive painless cervical lymphadenopathy, although any nodal station can be affected. RDD can also manifest as histiocyte-rich soft-tissue infiltrates in any organ system. Multiple varied pathologic conditions, including autoimmune and hereditary disorders and even malignancies, can coexist with RDD and thus further confound the clinical findings. Radiologic findings often provide the first clue to the presence of RDD by detecting nonspecific lymphadenopathy or masslike extranodal disease. However, imaging findings are nonspecific, similar to the clinical manifestations, and are best interpreted in conjunction with histologic features. Imaging allows determination of target sites for biopsy and the extent of the disease, helps predict prognosis, and assesses treatment response. The rarity of the disease and a lack of uniform guidelines make management challenging. Nevertheless, radiologic findings help assess treatment response and guide further management. The authors discuss various radiologic findings of RDD, along with differential diagnoses, by using an organ system-based approach and briefly describe the consensus management guidelines for RDD discussed in the 2016 annual meeting of the 32nd Histiocyte Society. ©RSNA, 2026 Supplemental material is available for this article.

Occult breast cancer (OBC) is a rare condition presenting with axillary or distant lymph node metastases without a detectable primary tumor. Immune checkpoint inhibitors (ICIs) show promise in triple-negative breast cancer (TNBC) treatment; however, their efficacy in OBC remains unclear. The present study describes the case of a 71-year-old woman who presented with left cervical and axillary lymphadenopathy. [18]F-fluorodeoxyglucose positron emission tomography-computed tomography (CT) and breast ultrasonography revealed no detectable primary breast lesion. Core needle biopsy of the axillary lymph node confirmed the diagnosis of TNBC (estrogen receptor, 0%; progesterone receptor, 0%; human epidermal growth factor receptor 2 score, 0). The programmed death-ligand 1 combined positive score was >10. Since the patient had stage IV disease with the biological subtype defined by lymph node biopsy, breast magnetic resonance imaging was not performed to avoid delaying systemic therapy. Pembrolizumab (Pembro) combined with gemcitabine and carboplatin was initiated. However, the patient developed a Grade 1 rash after the first cycle and diarrhea after the second cycle, followed by immune-related colitis requiring hospitalization. Notably, the emergence of immune-related adverse events (irAEs) paralleled a marked treatment response, with non-contrast CT after three cycles showing complete resolution of left axillary lymph node metastases. Pembro was discontinued, and the patient has maintained a complete response on eribulin monotherapy for >1 year. The present case suggests an association between irAEs and the clinical effectiveness of ICIs, highlighting the potential of Pembro-containing chemotherapy for OBC treatment, and emphasizing the importance of prompt irAE recognition and management. Lymph node-dominant disease may represent a particularly immunogenic context for ICI therapy.

We report the 18F-FDG PET/CT findings of IgG4-related autoimmune hepatitis mimicking hepatic malignancy in a 52-year-old man. The patient presented with intermittent fever, abdominal pain, and significantly elevated tumor markers. Initial evaluation with contrast-enhanced CT suggested hepatic malignancy. 18F-FDG PET/CT demonstrated heterogeneous hepatic FDG uptake and multiregional hypermetabolic lymphadenopathy. Diagnosis was confirmed by cervical lymph node biopsy and a favorable clinical response to glucocorticoid therapy.

Although it is extremely rare, papillary thyroid carcinoma (PTC) can exhibit unexpected behavior, with the potential to transform into more lethal forms in metastatic sites. This report describes 2 cases in which PTC transformed within metastatic lymph nodes. Case 1: A 57-year-old woman with a progressively enlarging right neck mass was found on imaging to have cervical lymphadenopathy and small right thyroid nodules. She underwent total thyroidectomy with neck dissection. Histopathology revealed metastatic PTC with squamous dedifferentiation in cervical nodes. Immunohistochemistry confirmed thyroid origin. Case 2: A 45-year-old woman presented with right submandibular swelling. Ultrasound revealed a left thyroid nodule with suspicious cervical lymphadenopathy. She underwent total thyroidectomy with neck dissection. Histopathology showed conventional PTC with high-grade transformation in 1 metastatic lymph node, consistent with differentiated high-grade thyroid carcinoma. Seven cases of PTC transformation in metastatic sites were reviewed. Ages ranged from 56 to 79 years. Symptoms were neck masses, respiratory, and systemic symptoms. Most cases were conventional PTC. Transformation predominantly resulted in squamous cell carcinoma, though rarer transformations were present. The transformations were mainly regional, but distant metastatic sites such as the lung were also reported. Management included total thyroidectomy and neck dissections with radioactive iodine, often combined with chemoradiation or targeted therapy for advanced cases. Lymph node metastases originating from the thyroid may undergo histological transformation and exhibit aggressive behavior. Total thyroidectomy combined with radioiodine ablation and hormone therapy might yield favorable outcomes, but regional and distant metastases may still develop.

We report the case of a man in his 30s who presented with exertional dyspnoea and dry cough for 18 months, along with fever and generalised lymphadenopathy (cervical and axillary) for 3 months. He had no feature indicating a connective tissue disorder. High-resolution CT of the chest revealed bilateral and diffuse thin-walled cysts with multiple mediastinal lymph nodes, consistent with a cystic interstitial lung disease. His pulmonary function test showed a severe restrictive disease and an autoimmune workup revealed strong positivity for anti-SSA/Ro52. Minor salivary gland biopsy showed lymphocytic foci with a focus score of >1. Based on the 2016 American College of Rheumatology-European Alliance of Associations for Rheumatology (ACR-EULAR) classification, the patients' diagnosis of Primary Sjögren's was confirmed. A transbronchial lung biopsy on histopathology showed diffuse polyclonal lymphoplasmacytic interstitial infiltration with germinal centre formation, consistent with lymphocytic interstitial pneumonia. In view of the extensive lymphadenopathy, lymphoma was systematically ruled out through lymph node excision, bone marrow examination and serum electrophoresis, all of which supported a benign reactive process. The patient was diagnosed with lymphocytic interstitial pneumonia and pseudolymphomatous lymphadenopathy as the initial manifestation of primary Sjögren's syndrome and showed clinical stability following treatment with systemic corticosteroids and mycophenolate mofetil.