1. Introduction

Dapsone is an antibiotic of the sulfone family with bacteriostatic, anti-inflammatory and immunomodulatory effects. As an antibacterial, it inhibits bacterial synthesis of dihydrofolic acid via competition with para-amino-benzoate for the active site of dihydropteroate synthetase. The anti-inflammatory and immunomodulatory effects are still not fully understood and it’s thought the to act through the blockade of myeloperoxidase. It’s effective in inflammatory diseases that have in common an infiltration of large numbers of polymorphonuclear leukocytes, predominantly neutrophils [1,2].

There is no solid evidence to recommend treatment in MCD. MCD usually has a chronic course with exacerbations and remissions and treatment is often unsuccessful [3,4]. Corticosteroids and antibiotics (mainly metronidazole) are the most used therapies described in the literature [3-5]. Biologic therapies have become an important tool for managing a number of inflammatory dermatoses, and are often used to sustain remissions of CD. Their use for the treatment of MCD has also been recognized. Specifically, the TNF-alfa inhibitors adalimumab and infliximab have been used successfully in cases of MCD refractory to traditional therapies [6-8] never the less, its use in our country is limited by the high cost. The use of dapsone has been mentioned in few cases of cutaneous manifestations of CD, but not as treatment in MCD [1,2].

2. Case Report

An 82-year-old woman diagnosed with Crohn’s disease 20 years ago with colostomy due to total proctocolectomy, presented with a 2-year story of painful lesions on her groin, genital region and gluteal cleft, with exacerbations and partial remissions. 10 years ago she had similar lesions in her infraabdominal fold with spontaneous resolution (Figures 1-3).

On examination, erythematous plaques with shiny surface, erosions and multiple ulcers with little purulent exudate were seen in the mentioned areas. Routine laboratory tests were normal. Skin biopsy showed perivascular and periadnexal noncaseating granulomas, with numerous giant cells and dermis with perivascular lymphocytic infiltration. The diagnosis of metastatic Crohn’s disease was made.

We first started topical therapy with corticosteroids and antibiotics along with oral prednisone (0.5 milligram per kilogram per day). There was no significant improvement, so a change to dapsone was made, raising the dose up to 150 milligram per day with fast and significant response, achieving almost full remission in three months (Figure 5,6).

3. Discussion

MCD is considered a rare disease, therefore it doesn’t exist enough evidence to support any specific treatment, although multiple case-report therapies have been informed as successful [3-5]. Even though spontaneous resolution of MCD has been described, it is infrequent and unpredictable, usually behaving as a chronic disease with multiple relapses. Medical treatment is frequently unsuccessful [3,4].

It is essential not just to treat MCD, but to manage with expertise CD, as this varies severity of the presentation. A retrospective review of 700 cases of CD suggested that skin lesions occur more frequently in patients with colon involvement compared with those having ileal involvement alone [9] this finding was supported by a subsequent large review [10].

It is important to highlight that surgical resection of the affected bowel does not guarantee resolution of CD nor the skin lesions [3,4,11]. Severity of EC is not correlated with skin manifestations [3,12,13]. Most investigators have failed to detect a connection between the activity of skin and GI lesions [14,15].

MCD is considered an autoimmune chronic inflammatory disease, and the first choices of treatment are immunosupressors. Corticosteroids are considered the first line of treatment, either topical of high potency, or oral as prednisone 30 mg/day, with progressive reduction. There are reports in literature that validate the use of oral metronidazole in high doses 800-1500 mg/day for at least 4 months. Other drugs such as metotrexate, azatioprine, ciclosporine and tacrolimus have also been used. In refractory MCD, biological treatment has been used (infliximab yadalimumab) [3,4,5,16].

There are no randomized clinical studies nor case reports of dapsone efficacy in MCD. The only information available is of its use in managing CD and skin lessions secondary to CD and refractory to conventional treatment. Cutaneous manifestations of CD not MCD respond well to treatment with dapsone, achieving full recovery in most cases [17-20].

Given the similar pathophysiologic and histology between EC and MCD, we thought dapsone to be a valid therapeutic option in view of the results previously described.

Dapsone toxicity may be categorized as either dose-dependent or idiosyncratic reaction. Most of the side effects are dose related and uncommon at doses lower than 100 mg/day. It’s relevant to mention that the most dangerous adverse effects of dapsone are DRESS syndrome and hematologic alterations such as methemoglobinemia, aplastic anemia, leukopenia, agranulocytosis, eosinophilia, macrocytic anemia and Heinz

bodie, which are dose-dependent and more common and severe in patients with gluclose-6-phosphate dehydrogenase deficiency. Patients generally tolerate 100 mg/day with very little hemolysis, at doses of 200-300 mg/day all patients develop hemolysis [1,2].

In summary, in MCD refractory to first line treatment with corticosteroids and metronidazole, dapsone should be considered as an alternative, taking into account the full recovery observed in our patient and the evidence available in the literature. Unfortunately, there is no solid evidence for it to be recommended, bearing in mind the low frequency of this disease, which complicate investigation.

Figure 1: Lesions in the groin and genital area

Figure 2: Lesions in the genital area

Figure 3: Lesions in the gluteal cleft

Figure 4: Lesions in the genital region after treatment with dapsone

Figure 5: Lesions in the groin after treatment with dapsone

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