Secondary bone lymphoma
Two months low back pain, night sweats and loss of weight.
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Ill-defined abnormal low T1 / high T2 signal throughout both iliac bones, right greater than left, with associated patchy postcontrast enhancement. No large extra-osseous mass. On the right, the signal change abuts the right sacro-iliac joint without joint destruction, effusion or extension into the sacrum. Periosteal enhancement and fluid surrounds the signal change in both iliac bones extending around the iliacus muscles bilaterally as well as along the posterolateral aspect of the right psoas major muscle. No further focal osseous lesions.
Pelvic viscera are within normal limits. No pelvic free fluid. No enlarged pelvic sidewall or inguinal lymph nodes. Femoral neurovascular bundle is normal. No inguinal or femoral hernia.
The patient proceeded to a PET-CT (not shown), which demonstrated avid FDG uptake in both iliac bones along with avid uptake in enlarged cervical lymph nodes. The patient proceeded to lymph node biopsy.
MACROSCOPIC DESCRIPTION: "Cervical lymph node": A lymph node 12x12x11m with a nodular grey cut surface and rubbery texture. A3. (YS)
MICROSCOPIC DESCRIPTION: Sections show a lymph node with surrounding fibroadipose tissue. There is extensive areas of central lymph node necrosis. No granulomas are seen. The nodal architecture is effaced by a population of malignant medium to large lymphoid cells. Tumor cells contain amphophilic cytoplasm, oval nuclei with coarse granular chromatin and small nucleoli. Frequent apoptotic bodies are present, imparting a "starry sky" appearance. Immunohistochemical results show tumor cells stain: POSITIVE: CD20, CD79a, BCL-6, MUM1, CMYC (50%). NEGATIVE: CD3, CD5, CD10, BCL-2, CyclinD1, EBER-CISH, Tdt. The Ki67 proliferation index is approximately 80-90%.
DIAGNOSIS: Cervical lymph node, excisional biopsy: Diffuse large B-cell lymphoma, activated B-cell phenotype.