CASE REPORT: TATTOO GIVING THE DIAGNOSIS OF RENAL SARCOIDOSIS

Introduction:

Renal limited sarcoidosis is an uncommon presentation. Although the aetiology of sarcoidosis is unknown, it typically occurs with pulmonary, ocular, and skin manifestations. In this case presentation, we aim to guide through how a tattoo changed a patient’s diagnosis from Drug-Induced acute Tubulointerstitial Nephritis (TIN) to Renal Sarcoidosis (RS). A 51-year-old Caucasian female patient was referred to Hospital by GP after bloods showed an incidental finding of acute kidney injury with an estimated Glomerular Filtration Rate (eGFR) of 6 mL/min – all other blood tests, including C-Reactive Protein, bone profile, and full blood count, were normal. She had been experiencing fatigue for 5 weeks, unexplained weight loss 3 weeks prior, and polydipsia. She had been taking painkillers including nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPI) for lumbar spinal radiculopathy. Examination: No oedema. Abdomen soft, non-tender with no organomegaly. No palpable lymphadenopathy. Heart sounds were normal. 

Methods:

To review this unique case, we used our local programmes, EPR and Vital Data, to review clinical notes. Radiology scan reports were obtained from the local radiology software, PACS. Histology images were obtained from the histopathology department. Literature search using terms “sarcoidosis AND tattoo” and “sarcoidosis AND renal” on ScienceDirect and PubMed. 

Results:

Renal screen including HIV, Hepatitis B and C, ANA, ANCA, Complement C3 and C4, GBM-Ab, immunoglobulin and electrophoresis were all inconclusive. An ultrasound scan of her kidneys was unremarkable showing normal sized, unobstructed kidneys. Admission chest X-Ray identified normal lungs, normal heart size and no mediastinal abnormality. CT scan of her thorax, abdomen and pelvis identified splenomegaly and numerous mediastinal, abdominal and para-aortic lymph nodes, although all of these are sub-centimetre. She underwent a kidney biopsy, depicted in Figure 1, which showed acute granulomatous tubulointerstitial nephritis – (predominantly lymphocytic TIN) with some eosinophils and non-caseating granulomas; this was deduced to be secondary to NSAIDs and PPIs, given her history of recent use of these medications. Although interstitial non-caseating granulomas confined to the renal cortex is a good diagnostic marker for renal sarcoidosis, these are not specific and could be drug induced too. Differential diagnosis of lymphoma and sarcoidosis was suggested in the context of the splenomegaly and lymphadenopathy. As a result, she underwent a bone marrow biopsy to investigate lymphoma; this was essentially normal. After ruling out lymphoma as the most likely cause of her AKI, lymphadenopathy and splenomegaly was thought to be reactive and secondary to PPI and NSAIDs induced acute interstitial nephritis, for which she was treated with steroids.

Conclusions:

Prednisolone 30mg once daily (OD) was initiated with preliminary improvement in her renal function but steroids were slowly weaned then discontinued once her renal function plateaued at eGFR 13 mL/min – seen in Figure 2. As she had interstitial fibrosis and tubular atrophy of 80%, evident on her kidney biopsy, we did not continue her on immunosuppression for a prolonged period. Her renal function declined once off the steroids and thus she was restarted on Prednisolone 20mg OD. There was improvement of her renal function which, once again, plateaued at eGFR 13 mL/min and therefore they were weaned and discontinued. At this time, the patient was being worked up for peritoneal dialysis with plans for a renal transplant. During a clinic appointment, the patient mentioned that her tattoos were inflamed and raised since discontinuation of the steroids which lead to the investigation and literature search into RS. Granulomatous interstitial nephritis and hypercalcemia-related disorders are the main kidney abnormalities in sarcoidosis. Skin manifestations of sarcoidosis are typically erythema nodosum and Lupus perino, however cutaneous sarcoid reactions involving tattoos is known; figure 3 shows the sarcodial tattoo reaction that this patient experienced. In conclusion, RS is a rare, isolated manifestation of sarcoidosis but cutaneous manifestations, in particular tattoos that are raised and inflamed, can aid the diagnosis along with non-caseating granulomas on kidney biopsy and splenomegaly and lymphadenopathy on cross sectional imaging. 

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.