skin and soft tissue infections caused by non - tuberculous mycobacteria ( ntm ) , which used to be considered unusual , have become more frequent in recent times . atypical mycobacteria are environmental saprophytes , which may occasionally enter human skin through injuries and cause localized infection . papules , nodules , plaques , ulcers and panniculitis - like lesions are common manifestations . disseminated infection occurs in immunocompromised patients . this kind of cutaneous infection is not frequently seen in humans and its diagnosis can be missed unless there is a strong clinical suspicion coupled with microbiological confirmation . a 52-year old healthy upper middle class , italian male and his 21-year old daughter presented in may 2008 with a history of swelling on of the father 's face and neck , and on the daughter 's buttocks and legs . the swellings had started approximately three months previously , had gradually increased in size , associated with moderate pain . both subjects reported that they were swimmers and that they used to travel to egypt in the summer . on physical examination , the daughter had purple indurated subcutaneous nodules and plaques were observed on her right buttock . the father had subcutaneous granulomas on the lateral left side of his neck that had also ulcerated ( figure 1 ) . both patients reported intermittent discharge from the lesions and associated local non - tender lymphadenitis . diagnostic aspiration from the swelling had been performed approximately 20 days previously after which the swelling had subsided . the cytological findings of the aspirate were inconclusive and the swelling recurred within the following few days which led to the patients returning for a repeat evaluation . laboratory evaluation , including wbc count , chain protein reaction ( cpr ) and antistrept olysin o titre ( as(l)o titre ( asot ) , showed no increase in values . liver , renal function tests and a chest x - ray were within normal limits . needle aspiration from the swelling was repeated and subjected to cytological and microbiological evaluations which showed cream colonies that turned yellow when exposed to light . a repeated skin biopsy specimen of the abscess wall showed an acute - on - chronic infection with edematous granulation tissue and some foreign - body giant cells . molecular diagnosis can identify species of mycobacteria polymerase chain reaction - restriction fragment of the hsp65 gene . after two months of treatment , the lesions healed completely . at 1-year follow up , there was no recurrence of the disease . ( b ) a painful abscess with associated erythema and edema of the right buttock . 
  ( a ) ( b ) a painful abscess with associated erythema and edema of the right buttock . two well - known species , m. tuberculosis and m. leprae , have been known for centuries to cause immense human suffering . the pathogenic potential of most other mycobacteria , present in the environment as saprophytes , has been recognized since the beginning of the 20 century . it is a waterborne mycobacterium that commonly infects fish and amphibians all over the world . categories at risk are home - aquarium enthusiasts , swimmers , aquarium staff , marine - life handlers , anglers , and oyster workers . in most cases , they present as a granulomatous infection localized in the skin , typically following minor trauma and other surgical procedures . the usual presentation is trauma to the skin in non - chlorinated water or salt water , and after about two weeks of inoculation it will develop into a localized papulonodular lesion which eventually ulcerates . the clinical syndrome is variable , the pathology is non - specific and culture is needed for definite diagnosis . infections sometimes heal spontaneously , but drug treatment is usually necessary for several months in order to cure the infection . knowledge of the relative frequency of post - travel related skin disorders , including their geographical and demographic risk factors , will allow for effective pre - travel counseling , as well as improve post - travel diagnosis and therapeutic intervention . in our patients , suspicion was aroused because they were swimmers who used to travel to egypt during the summer and had reported contact with aquatic animals , although they could not recall how many months after the trip the lesions appeared . clinicians seeing patients post - travel should be alert to travel - related skin diseases . to prevent and manage skin - related morbidity during travel , international travelers should avoid direct contact with sand , soil , and aquatic animals . sometimes lesions are aspecific and appear many months later so it is important to keep record of any traveling and seek immediate medical care . with the increased numbers of immunocompromised patients , it is likely that we will see a rising trend in these infections . a high index of suspicion is the key to diagnosis and appropriate samples should be sent for mycobacterial culture before the use of antibiotics .