Herpes simplex virus type II infection of ileum mesothelium : A case report and review of the literature

Departments of 1Pathology and Laboratory Medicine; 2Internal Medicine, Peter Lougheed and Foothills Medical Centres, Calgary, Alberta Correspondence and reprints: Dr SAC Medlicott, Calgary Laboratory Services, Peter Lougheed Centre, 3500 – 26th Avenue Northeast, Calgary, Alberta T1Y 6J4. Telephone 403-943-4907, fax 403-291-2931, e-mail shaun.medlicott@cls.ab.ca Received for publication December 7, 2004. Accepted March 28, 2005 SAC Medlicott, VG Falck, KB Laupland, et al. Herpes simplex virus type II infection of ileum mesothelium: A case report and review of the literature. Can J Gastroenterol 2005;19(6):367-371.

G astrointestinal herpes simplex virus (HSV) infection is predominantly a disease of the esophagus in immunodeficient patients.Patients are usually asymptomatic but may experience odynophagia, retrosternal chest pain or fever (1).Reported cases of disseminated HSV infection in immunocompetent patients are commonly complications of pregnancy (2).However, rare anecdotal case reports describe HSV viremia, proctocolitis and hemorrhagic cystitis in patients with diabetes mellitus (3)(4)(5).
The standard gastrointestinal pathology literature describes HSV infection as a localized phenomenon confined to the epithelial tissue circumscribing ulcers (6).However, few studies describe typical findings of disseminated HSV and its tropism within the gastrointestinal tract.
We report a case of disseminated HSV infection of the lung that also complicated ischemic adhesive band disease of the ileum.This patient was predisposed to disseminated HSV infection due to several autoimmune illnesses: type I diabetes, hypothyroidism and celiac disease.HSV cytopathic effect was identified histologically in the ileum mucosal ulcer bed and serosal cellular exudates.Immunohistochemistry (IHC), in situ hybridization (ISH) and conventional and real-time polymerase chain reaction (PCR) confirmed a HSV type II infection.
HSV cytopathic atypia and HSV IHC staining was confined to myofibrocytes and mesothelial cells without involvement of epithelium.HSV was isolated in bronchial secretions postoperatively by direct fluorescence antibodies.To our knowledge, this is the first documentation of the distribution of HSV cytopathic changes in the ileum of a patient with symptomatic disseminated HSV infection complicating type I diabetes.Our case portends that disseminated HSV infection can have a viral cytotropism differing from that of a localized epithelial HSV gastrointestinal tract infection.

CASE PRESENTATION
A 53-year-old Caucasian woman with chronic type I insulindependent diabetes, hypothyroidism and hypertension developed clinical and radiological features of a small bowel obstruction.A diagnosis of celiac disease was established on endoscopic biopsy five months before her latest hospital admission.She responded rapidly to a gluten-free diet and upon admission denied symptoms that could be attributed to celiac disease.She had been diagnosed with hypothyroidism several years previously and was asymptomatic on adequate thyroid replacement therapy.She had a history of oral cold sores and human papilloma virus cervical dysplasia.Medications included clopidogrel 75 mg per day, insulin (neutral protamine Hagedorn: 16 U every morning and 14 U every night; Humulin-R [Eli Lilly Canada Inc]: 8 U to 15 U every morning and 8 U to 14 U every night) and losartan 25 mg per day.Her past surgical history was significant for resection of an ovarian fibroma, an iliac vein thrombectomy, caesarian section and appendectomy.
One week before admission, she was diagnosed with bronchitis and treated with an oral antibiotic.She subsequently developed nausea, vomiting, bloating, abdominal distension and tenderness.She was admitted to the surgical unit for a small bowel obstruction that was confirmed radiologically.
Laparotomy identified right lower quadrant adhesive band disease.The ileum had perforated at a congested and strictured segment that was tightly applied to peritoneal adhesive bands.An end-to-end primary anastomosis was performed.
She remained febrile postoperatively despite receiving piperacillin and Tazocin (Wyeth, Canada) 3.375 g intravenously every 6 h.Hypoxic respiratory failure developed on day 2 postsurgery.She was transferred to the intensive care unit with presumptive adult respiratory distress syndrome, intubated and ventilated.Confirmation of HSV overgrowth at the bowel perforation site (by histology, IHC, ISH and PCR) and in bronchial secretions (direct fluorescence antibody) prompted intravenous acyclovir therapy.She defervesced two days later with improvement of hypoxia and the radiological pulmonary infiltrates.At no time were mucocutaneous vesicles identified in oral, genital or perianal sites.A negative lumbar puncture excluded encephalitis.Serology was negative for HIV and immunoglobulin subsets were normal.She had a complicated course and care was withdrawn 23 days after admission.

In situ hybridization
Dewaxed and dehydrated sections were digested with 100 µL of pepsin (Carezyme II, Biocare Medical, USA) at 37°C for 5 min.Slides were rinsed in Tris-buffered saline, dehydrated in ethanol and air dried.Ten microlitres to 20 µL of biotin-labelled HSV type I, HSV type II, CMV and adenovirus probes (ENZOLife Sciences Inc, USA) were placed on slides and cover slipped.The sections with probes were denatured at 95°C for 5 min and the slides incubated at 37°C overnight.After hybridization, slides were washed in Tris-buffered saline until the cover slips detached.Digoxigenin-labelled hybrids were then identifiable by the ENZO detection kit (ENZOLife Sciences Inc).The slides were then counterstained with hematoxylin and cover slipped.
Real-time (light cycler) PCR used DNA extracted from paraffin blocks according to the QIAamp DNA Mini Kit (Qiagen, Canada) recommendations.Extracted DNA was tested on the LightCycler employing the LightCycler HSV ½ Detection Kit (Roche Diagnostics, Canada) and its recommended parameters.Melting curve data were generated and analyzed by the LightCycler software.

RESULTS
The laboratory received an 11.2 cm bowel segment fixed in a "U-shape" due to serosal adhesions.A central stenosed region had a transverse 2.4 cm defect with exudates coating adjacent serosa.Mucosal tissue surrounding the defect was congested.The impression was one of infarction and perforation of an externally compressed segment of small bowel.
Histological assessment revealed a nondescript mucosal ulcer with a granulation tissue base and overlying cellular exudates.Ulcer borders were sharply delineated by intact mucosa.The ulceration extended into the muscularis propria and its focal attenuation was the perforation site.Acute serositis was demonstrated by prominent purulent exudates coating reactive mesothelium.
High power examination of the submucosal ulcer bed delineated rare spindle shaped cells with a ground glass nuclear appearance, circumscribed by a rim of dense chromatin.These cells also had irregular nuclear membranes and were occasionally multinucleated.Similar cytopathic atypia was in the vicinity of the serosa beneath the ulcer.No viral atypia was detected in endothelial cells or mucosal epithelium.
Cells with viral cytopathic effect in the ulcer bed had a HSV type I, HSV type II, vimentin and a focally actin-positive IHC phenotype.Such cells were negative for CMV, CD1a, CD68, CD45, CD20, CD31, S-100 and PGP9.5.Serosal cells with viral inclusions were HSV type I-, HSV type IIand calretinin-positive.These cells were also negative for those antigens that ulcer bed cells failed to react with.
ISH and PCR detected HSV DNA with a melting point characteristic of HSV type II (Figure 1).No CMV, adenovirus or VZV genetic material were detected.

DISCUSSION
HSV infection of adulthood is predominantly a disease of the immunocompromised (8).In the bone marrow transplant population, 70% of seropositive patients will reactivate, usually within the first month (8).These patients commonly have oral/genital mucositis with or without esophagitis (9).The rare patient develops HSV dissemination, primarily manifesting as encephalitis, pneumonia or hepatitis (8).
HSV infection in immunocompetent patients is usually a localized mucocutaneous or neural ganglia disease (13).However, data suggest that subclinical dissemination may be common.Acute HSV infection of genitalia is associated with a mild elevation of aminotransferases in 14% of otherwise healthy adults (14).HSV DNA has been isolated in the serum of 20% of healthy adults experiencing recurrent herpes labialis (15).
The origin of disseminated HSV infection is presumably an extension of oral/genital mucositis or reactivation of neural ganglia latent virus (3).It is postulated that isolated visceral HSV disease may be related to: a large viral load at the time of primary exposure; subtle host T cell/macrophage deficiencies; reinfection by a second strain; and/or existence of viscerotropic strains (16).
Gastrointestinal HSV infection is primarily an esophagitis, but proctitis is common as a sexually transmitted illness (17)(18)(19).HSV infection is usually restricted to the anorectum in the homosexual population, but rare examples of fulminant left-sided colitis have been identified (20,21).Of the 10 reported cases of HSV enteritis/colitis diagnosed antemortem, seven subjects were immunocompromised or on immunosuppressive therapy (9,(21)(22)(23)(24)(25)(26).One of the remaining three had type IIb diabetes mellitus as a predisposing condition (4).One patient had confirmed Epstein-Barr virus pharyngitis and another had undergone colon carcinoma resection two months previously (20,27).Our patient is the second reported case of herpes enteritis/colitis complicating diabetes mellitus (Table 1).
Figure 1) Polymerase chain reaction identifies herpes simplex virus (HSV) DNA in the bowel (two separate paraffin blocks, A3 and A4) and real-time polymerase chain reaction delineates its melting point to be that of HSV type II HSV enterocolitis manifests as abdominal pain with diarrhea (20,21,23,25,26).Bloody diarrhea and an acute abdomen are less common symptoms (9,20,27).Bowel perforation was identified in three of the 10 reported cases (23,24,27).A slight majority of patients had associated oral/genital mucositis (six of 10) and their symptoms resolved with acyclovir or gancyclovir therapy (six of 10) (9,(20)(21)(22)(23)(24)(25)(26)(27).Our case of HSV pneumonia complicated by HSV-infected ileal adhesive band disease similarly resolved after surgery and intravenous acyclovir therapy.However, our patient is unique in that bowel symptoms were those of obstruction, indicating that HSV enteritis was a secondary infection of ischemic bowel.
Classical histology of HSV infection is multinucleated or single cells having Cowdry type A inclusions and ground glass nuclear changes.Cowdry type A bodies are red intranuclear inclusions with a clear halo.Chromatin is relegated to the periphery as a rim of clumped nuclear material.It is commonly regarded that HSV cytopathic atypia is restricted to epithelia, specifically, those cells circumscribing mucosal ulcers (6).This viral effect is typical of primary cutaneous and esophageal lesions.
To our knowledge, this was the first documentation of HSV type II infecting the mesothelium.This finding was not surprising because other herpes virus subtypes are known to infect mesothelium.Human herpes virus-8 was identified in mesothelial cells of three of five patients with pleural effusions and Kaposi's sarcoma or Castleman's disease in a recent publication (28).

CONCLUSIONS
This was a unique case of disseminated HSV type II complicating adhesive band disease.Although HSV type II can disseminate systemically in insulin-dependent diabetes mellitus, this was the first documentation of viral cytopathic atypia in an ileal ulcer bed of such a patient.Previous studies have suggested that HSVinduced cytopathic atypia is generally confined to the intestinal epithelial cells at the perimeter of an ulcer.We report that disseminated HSV type II infects various intestinal cell lineages including myofibrocytes and mesothelium about an ulcer bed, in the absence of intestinal epithelial cell involvement.

ACKNOWLEDGEMENTS:
The authors thank Dr Demetrick's laboratory at the University of Calgary, Calgary, Alberta for their expert molecular analysis of the bowel specimen.We would also like to thank Ms Katina Haynes for helping prepare this manuscript for publication.

TABLE 1
Cases of antemortem herpes simplex virus (HSV) enteritis/colitis published in the English literature BMT Bone marrow transplantation; CMV Cytomegalovirus; F Female; GI Gastrointestinal; GVHD Graft-versus-host disease; IHC Immunohistochemistry; M Male