Fungal inflammatory masses masquerading as colorectal cancer: a case report

Non malignant invasive tumors of the colon and rectum are very rarely seen in clinical practice. More than 95% of all invasive tumors of the colon and rectum are adenocarcinomas. Atypical presentation of lesions in the colon and rectum include squamous cell cancers, carcinoid tumors, sarcomas and lymphomas. Basidiobolomycosis of the gastrointestinal tract should be considered when both carcinomas, sarcomas and lymphoma are ruled out and other causes are being considered. It should be within the list of differential diagnosis while evaluating patients with small bowel, colonic and rectal masses of unclear origin particularly in endemic regions of basidiobolomycosis including southwestern United States.

Basidiobolomycosis is caused by Basidiobolus ranarum, a saprophytic fungus found in the environment worldwide. It is a member of the order Entomophthorales of the class Zygomycetes [1,2]. Clinical spectrum of diseases from Basidiobolomycosis usually include skin and subcutaneous lesions presenting as indurated lesions affecting extremities, trunk and gluteal region only [3,4]. Inoculation from minor trauma or insect bites appear to be the mode of acquisition of the fungus [5-7]. Unintentional ingestion of the fungus from contaminated soil or fruits or vegetables is touted as the route of entry preceding GIB. Although living in tropical and subtropical areas are well established as risk factors for basidiobolomycosis, no risk factors are identifiable for GI basidiobolomycosis per se. Incidentally, basidiobolomycosis affects men more likely due to their indulgence in outdoor activity compared to women in the tropics.

Literature review by Vikram et al. [8] showed 44 cases of GIB in the previous 30 years [8]. Most of the cases reported are from Arizona and Saudi Arabia. Most of these patients were diagnosed with abdominal mass on CT scan and endoscopy after having been evaluated for indolent non specific signs and symptoms. Patients were normally immunocompetent men with no underlying serious medical problems. Routine laboratory work up showed peripheral eosinophilia. Diagnosis were confirmed by culture of tissue specimens. GIB involved colon (82%); small bowel (36%) and liver and gallbladder (30%). 84% patients underwent surgical excision of the masses and were treated with antifungal agents. 80% of patients survived following the above management.

There have been 17 previous reports of GIB from Arizona since 1997. Two other cases have been reported from Utah and Florida [9]. Case control study conducted by Center for Disease Control and Prevention (CDC) showed the following potential risk factors for GIB: Prolonged residence in Arizona, prior treatment of peptic ulcer disease, diabetes, outdoor activities including gardening and landscaping [10].

Case series by Saud Al Shanafey reported 9 pediatric cases of GIB at King Faisal Specialist Hospital and research center between 2001 and 2010 [11]. Distribution of lesions included left colon involvement in 11%, right colonic involvement in 33%, liver involvement in 78% and diffuse abdominal disease in 22%. Patients with colonic involvement in GIB had right or left hemicolectomy. Liver lesions were managed with partial hepatectomy. One patient who had multiple smaller lesions in both lobe of the liver was treated with antifungal medications successfully. It is interesting to note that 89% of the patients were of male gender. These patients had a median workup for 4 months before being diagnosed with GIB. Clinical presentation generally included vague abdominal pain, fever, change in bowel habits, weight loss and palpable abdominal mass. Tests showed patients to have leukocytosis, eosinophilia, raised ESR and CRP. Two patients had disseminated abdominal disease and died despite aggressive management. All the surviving patients were treated with long term antifungal medications. Pediatric GIB has also been reported by Al Jarie et al. and others [12-14].

Management of GIB depends on the clinical presentations. Patients who present with complete bowel obstruction would need emergent surgery to relieve the obstruction. Failure to identify and appropriately treat this rare diagnosis has been complicated by acute colonic obstruction necessitating emergency colostomy [13] and mortality [15]. Sub acute to chronic presentations (as in our patient) could be managed electively. Although Saud Al Shanafey et al. proposed early surgical intervention in patients with GIB to avoid morbidity and mortality, it may not be necessary when the presentation is rather less emergent. Anti fungal treatment alone may be sufficient to eradicate the lesion (as in our patient), but it would depend on the clinical presentation and the response of the lesion to antifungal treatment. If surgery is required, conservative resection to reduce the bulk of the lesion and to maintain GI and biliary continuity would be sufficient. This has been reported to improve response to medical management. Close follow up is recommended in the postoperative period to ensure eradication of the disease. Investigations during the follow up period would depend on the mode of presentation and the site of the lesion. Response to medical treatment of lesions involving the cecum, ascending colon and recto-sigmoid region can be evaluated with MRI of abdomen and pelvis.

Duration of treatment has not been standardized. Most of the patients have been treated with antifungal treatment ranging from 6 months to 1 year. Vikram et al. reported relapse with discontinuation of treatment after 3 months based on symptomatic improvement.

Diagnosis of basidiobolomycosis require culture of B ranarum from the tissue specimen. But, presumptive diagnosis could be made from the histopathological appearance. Microscopic appearance of B ranarum include scarce, broad and thin walled pleomorphic hyphae surrounded by collar of eosinophilic material known as Splendore­hoeppli phenomenon [16]. Susceptibility of Basidiobolomycosis to antifungal agents are known to be highly variable and isolate dependent [17,18]. Empiric treatment could be started with Itraconazole or Voriconazole, but susceptibility testing is recommended to ensure effective treatment. Taghipour et al. reported a mortality with GIB from septic shock and pulmonary insufficiency despite successful diagnosis and treatment with Itraconazole and amphotericin B. Surveillance of treatment response could be performed with MRI or CT scans. There are no consensus opinion on the imaging modality and duration of surveillance in the literature. We propose the surveillance imaging could be performed with CT scan or MRI scans depending on the local availability and expertise.

In summary, GIB is a rare invasive fungal infection involving the gastrointestinal tract and liver. If identified early and treated appropriately, it is curable and surgery can be avoided. Surgery is unavoidable if GIB is complicated by bowel obstruction. Awareness and knowledge is important for early diagnosis and treatment of GIB and prevent morbidity and mortality from delay in diagnosis.