ABSTRACT Background Acute tubulointerstitial nephritis (ATIN) is a very rare paraneoplastic manifestation in patients with multiple myeloma (MM). It is an uncommon pattern of renal disease in such patients. Case presentation We report a case of an 82-year-old male who was admitted with acute kidney injury. Renal biopsy showed typical findings of light chain-associated ATIN with scattered inflammatory cells in the interstitium and associated active tubulitis. No other common manifestations of MM were present at the time of presentation, including hypercalcemia, hyperuricemia, proteinuria, bone pain or lytic bone lesions. Subsequent immunoassays revealed significant serum lambda light chain burden and Bence Jones protein in urine. Immunofluorescence demonstrated linear tubular basement membranes with positive staining for lambda light chain (3+). Electron microscopy (EM) further showed interstitial edema and inflammation. All the aforementioned findings are consistent with ATIN and supported the diagnosis of MM. Conclusions In conclusion, light chain-associated ATIN should be considered in the differential diagnosis of acute interstitial nephritis. Henceforth, serum free light chains as well as serum and urine protein electrophoresis should be included in the workup of such patients.

The finding of a late flexion cetomimid specimen of 24.6 mm body length (BL), plus a caudal streamer of 5.7 mm, collected in the southeastern Pacific near the Juan Fernandez seamounts (33.565°S; 77.710°W), is reported. The specimen was in good condition, almost fully pigmented, covered by small melanophores from the head to the caudal streamer, where the pigmentation is denser. It possesses an upturned mouth, developing pelvic fins with a high insertion, 14 dorsal and 15 anal fin rays, 7+7 principal caudal fin rays, ca. 54 myomeres, and a preanal distance of 75% BL. Based on the available information, the specimen can be tentatively ascribed to a species of Gyrinomimus or Cetomimus.