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Confusable versus associated diseases


The words "confusable disease" and "associated disease" are always used in connection with another disease, in our situation in connection with BPS.

For BPS, a confusable disease is a disease which may show similar symptoms and/or signs to those of BPS. In general, such a confusable disease needs to be excluded as the main cause of the symptoms and/or signs before a diagnosis of BPS can be made. In practice, the situation may be more complex as the presence of a confusable disease does not necessarily exclude the presence of BPS as well. If both a confusable disease and BPS are present, it is clear that for individual diagnoses of patients and for epidemiological studies, the presence of a confusable disease should not exclude a diagnosis of BPS. For many scientific studies, on the other hand, e.g. for studies on the effect of a particular treatment, only patients with BPS without an additional confusable disease should be accepted as the confusable disease may severely interfere with outcome parameters of such a study.

BPS has several associated diseases. Associated diseases are diseases with a higher prevalence among patients with BPS than in the general population. This does not necessarily imply a causal relationship between BPS and the associated disease. The practical consequence of associated diseases is that medical professionals should know these associations and should have a high index of suspicion for the associated diseases.


General aspects of confusable diseases


Confusable diseases misdiagnosed as interstitial cystitis


  • A 73-year-old woman with chronic pelvic pain, burning toes, and an eighty-pound weight loss.
    Birnbaum J, Chai TC, Ali TZ, Polydefkis M, Stone JH. Arthritis Rheum 2008;59:1825-31. 
    • an elderly woman is described with a 5-year history of chronic bladder and pelvic pain, an 80-pound weight loss, a small fiber neuropathy, and interstitial lung disease
    • laboratory tests showed a strongly positive rheumatoid factor, and positive ANCA assays associated with perinuclear immunofluorescence and antigen specificity for myeloperoxidase.
    • bladder biopsies containing bladder mucosa showed no specific abnormalities
    • a (false) diagnosis of IC/PBS was made; only after a cystectomy was performed, a necrotizing vasculitis of medium-sized arteries was seen that led to the right diagnosis of microscopic polyangiitis (MPA); disease remission was obtained after adequate treatment for MPA
    • it is likely that if deeper bladder biopsies would have been done containing detrusor muscle at initial evaluation, the correct diagnosis could have been made 5 years earlier; moreover, the patient would also have received adequate treatment for a potentially fatal disease 5 years earlier and a cystectomy wouldn't have been necessary



  • Dysuria and a headache
    Lo S, Noble J, Bowler I, Angus B. Lancet 2004;364:1554
    • a case report of a 49-year-old white woman with symptoms of recurrent urinary tract infections; she had no other medical history of note and she had not traveled outside of the UK 
    • an initial diagnosis of interstitial cystitis was found to be wrong; despite she had no pulmonary disease, the cystitis was found to be due to infection withMycobacterium tuberculosis 



  • A referral center’s experience with transitional cell carcinoma misdiagnosed as interstitial cystitis.
    Tissot WD, Diokno AC, Peters KM. J Urol 2004;172:478-80
    • a retrospective review of patient records showed that between 1998 and 2002 a total of 600 patients were seen with the diagnosis of interstitial cystitis (IC) 
    • six patients (1%) previously diagnosed as having IC were found to have transitional cell carcinoma as the cause of symptoms, 4 of whom (67%) had no hematuria
    • the authors conclude that patients with irritative voiding symptoms require a thorough evaluation which may include cystoscopy, cytology and upper tract imaging; they expect that the number of wrong diagnoses of IC would increase if the criteria to diagnose IC and initiate treatment were oversimplified


Drug-induced cystitis

  • Eosinophilic cystitis induced by penicillin
    Tsakiri A, Balslev I, Klarskov P. Int Urol Nephrol 2004;36:159-61
    • a 30-year-old woman developed classic symptoms of painful bladder disease and eosinophilic cystitis as an adverse effect of penicillin for abdominal actinomycosis; the symptoms were reversible after stopping penicillin




Lupus Cystitis

General information on systemic lupus erythematosus

  • Systemic lupus erythematosus
    Rahman A, Isenberg DA. N Engl J Med 2008;358:929-39
    • a great review on genetic and epidemiologic factors, autoantibodies, tissue damage by autoantibodies, the role of T cells, source of the autoantigens, cytokines and implications for treatment


Relationship between BPS and SLE

  • Interstitial cystitis and systemic lupus erythematosus in a 20-year old woman.
    do Socorro Teixeira Moreira Almeida M, Carvalho LL, Carvalho AG, et al. J Rheumatol Int 2008 Aug 12. (Epub ahead of print] PMID: 18696074
    • a case report of a 20-year-old woman with systemic lupus erythematosus; she presented with dysuria, urinary frequency and suprapubic pain and was found to have a interstitial cystitis

  • Lupus cystitis on Ga-67 scans
    Lin WY, Lan JL, Wang SJ. Clin Nucl Med 2000;25:737
    • a 46-year-old woman with systemic lupus erythematosus had hematuria, fever, and proteinuria. She was transferred to the nuclear medicine department for evaluation of the disease activity of lupus nephritis. A Ga-67 scan showed increased radioactivity in both kidneys. Active nephritis was suggested. Furthermore, increased Ga-67 uptake in the wall of the urinary bladder was also noted. Lupus cystitis was indicated. A bladder biopsy confirmed the diagnosis.

  • Involvement of the urinary bladder in systemic lupus erythematosus. A pathologic study.
    Alarcon-Segovia D, Abud-Mendoza C, Reyes-Gutierrez E, et al. J Rheumatol 1984;11:208-10 
    • urinary bladder histologic changes were found in 16 of 35 necropsies from systemic lupus erythematosus (SLE) patients; these included interstitial cystitis (n = 11), hemorrhage (n = 9), congestion (n = 7), vasculitis (n = 5), and perivenular infiltrate (n = 4)

  • Similarity of interstitial cystitis to lupus erythematosus. 
    Fister GM. J Urol 1938;40:37-51

   Other bladder conditions  

  • Incomplete bladder emptying (retention)

   Gynaecological conditions  

  • Vaginal candidiasis


   Male diseases  




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