Case 19 cont'd
There was a recent CT Abdomen and Pelvis available for correlation, therefor we didn't perform SPECT-CT imaging for this particular case.
CT- Axial view
CT Findings:
There are multiple calcified lymph nodes involving retrocrural, paraaortic, mesenteric, and iliac regions, corresponds to the areas of moderate to intense uptake on bone scintigraphy within the abdominopelvic regions.
History:
This case was a 65-year-old man with CRPC and history of Xofigo therapy for bone metastases. Subsequently the patient developed multiple lymphadenopathies found on CT, presumably due to prostate cancer. Bone scan demonstrated interval improvement of bone metastases with multiple foci of high uptake in Abdomen and pelvis, corresponds to calcified lymph nodes on CT.
1. what are the underlying processes leading to calcium and MDP deposition within the soft tissue? the processes include metastatic calcification, dystrophic calcification, metabolic deposition and sequestration(1).
2. What is the mechanism of MDP uptake in malignancies within the soft tissue? Mechanisms of the neoplastic uptake of MDP were mainly related to necrosis and/or calcification, a rich blood supply and the osteoid matrix in tumors(2). When cells undergo necrosis, the mitochondria and endoplasmic reticulum in the cytoplasm swell to form vacuoles, which causes the accumulation of amorphous calcium densities in the mitochondrial matrix(2). Dystrophic Calcification occurs in patients with normal Ca2+ and PO4 levels and refers to Ca2þ deposition in tissues secondary to histologic disruption caused by trauma, ischemia, or cellular necrosis or in the enzymatic necrosis of fat(1). If necrotic cells and cell debris are not cleared in time, they will absorb calcium salts and other minerals, resulting in dystrophic calcification(2). The other possible mechanism of MDP accumulation is that there is increased blood flow to the neoplasm or abnormal calcium metabolism, which was affected by paraneoplastic syndrome(2).
3. Differential diagnosis of calcified lymph nodes: - Sarcoidosis - Histoplasmosis - Tuberculosis - Castleman disease - Amyloidosis - Malignancy: - Treated lymphoma - Osteogenic tumor - Mucinous tumor - GIST - Carcinoid - Thyroid malignancies - Head and neck squamous Carcinoma
References:
1.Zuckier LS, Martineau P. Altered biodistribution of radiopharmaceuticals used in bone scintigraphy. InSeminars in nuclear medicine 2015 Jan 1 (Vol. 45, No. 1, pp. 81-96). WB Saunders.
2.Liu S, Xie J, Yu F, Cai H, Wu F, Zheng H, Ma C, Lv Z, Wang H. 99mTc-Methylene Diphosphonate Uptake in Soft Tissue Tumors on Bone Scintigraphy Differs Between Pediatric and Adult Patients and Is Correlated with Tumor Differentiation. Cancer Manag Res. 2020 Apr 3;12:2449-2457. doi: 10.2147/CMAR.S241636. PMID: 32308481; PMCID: PMC7138625.