BACKGROUND: Light chain proximal tubulopathy (LCPT) is a rare form of paraprotein-related disease, occurring in two main histopathological forms; crystalline and non-crystalline. The clinicopathological features, treatment strategies and outcomes, especially of the non-crystalline form, are not well described. METHODS: Single-centre retrospective case series of 12 LCPT patients, 5 crystalline and 7 non-crystalline, between 2005-2021. OBSERVATIONS: Median age was 69.5 years (range, 47-80). 10 patients presented with CKD and significant proteinuria (median eGFR of 43.5 ml/min/1.73m2; uPCR 328 mg/mmol). Only 6 patients had known haematological disease at the time of renal biopsy. Multiple myeloma (MM) was diagnosed in 7 cases and MGRS in 5. A clone was detected in all cases combining serum/urine electrophoresis and free LC assays. Crystalline and non-crystalline variants had similar clinical presentations. For the non-crystalline variant, a diagnosis was reached based on combination of CKD without other cause, haematological work-up, LC restriction on IF and abnormalities on EM. Nine of 12 patients received clone-directed treatment. Patients who achieved haematological response (including all non-crystalline LCPT) had improved renal outcomes over a median follow-up of 79 months. CONCLUSIONS: The non-crystalline variant may go unrecognised because of its subtle histopathological features and requires EM to distinguish it from "excessive LC resorption without tubular injury". Clone-directed treatment with good haematological response improves renal outcomes in both variants but limited data exist in MGRS. Multi-centre prospective studies are needed to better define the clinico-pathological characteristics associated with poor outcomes and optimize treatment strategies in patients with MGRS.