A 27-year-old man presented with a 4-day history of non-migratory right lower quadrant pain to our emergency department. He was diagnosed with acute appendicitis with the help of computed tomography (CT) scan and he subsequently underwent a laparoscopic appendicectomy. His past history was significant in that he recovered from COVID-19 infection 2 months prior to presentation. The histopathological findings revealed features of lymphocytic type phlebitis, which is a rare finding. In this case, the histopathological features are reportedly similar to the features seen in veno-occlusive disease associated with liver disease related to COVID-19. Possible relationships between this patient’s COVID-19 infection and the unusual histology are considered.
Our patient did not have chronic abdominal pain symptoms or symptoms of inflammatory bowel disease. He had no history of autoimmune related disease symptoms. His background medical history included a previously investigated mild persisting neutropenia most likely a benign ethnic neutropenia.
He had both ultrasound and computed tomography scan imaging performed which confirmed appendicitis. Initial full blood count revealed a white cell count (WBC) of 3.8 × 109/L with predominantly a neutropenia of 1.4 × 109/L consistent with his known haematological history. He had a minimally elevated C-reactive protein (CRP) of 7 mg/L. All other blood parameters were normal.
We performed a laparoscopic appendicectomy on the same day as his presentation to our hospital. At the time of laparoscopy. We noted an abnormally dilated (75 mm in length and 15 mm diameter) and inflamed appendix with reactive peritoneal free fluid. There were no other unusual findings on laparoscopic assessment. Cytology of the peritoneal fluid revealed mesothelial cells, macrophages and lymphocytes. Our patient made an uneventful post-operative recovery.
Of incidental note, our patient had been diagnosed with COVID-19 2 months prior to this presentation. The diagnosis had been made on SARS-Cov2-RNA nasal and throat swab during an episode of flu-like symptoms. He was managed with community isolation and was predominantly asymptomatic for the duration of his isolation. He had remained asymptomatic in the interim period after clearance from the Public Health unit.
The histology showed features of an interval (chronic) appendicitis with transmural fibrosis with some areas of organisation. Of significant interest, there were focal areas of a lymphocytic phlebitis with some occlusion of the vessels. Elastic stains (EVG) highlighted the occluded vessels. Immunohistochemistry revealed only scattered plasma cells and there was no increase in IgG4 plasma cells. We were mindful of the fact that our patient was not diagnosed with a thrombus elsewhere.
Microscopic analysis showed areas of mucosal ulceration and architectural distortion of the appendiceal glands. There were areas of scattered large lymphoid aggregated extending to the mesoappendix with germinal centres. Patchy area of phlebitis was seen on EVG stain. Although the arterial structures were unremarkable, medium sized venules showed evidence of phlebitis. Immunohistochemistry for CD138 showed scattered plasma cells only on IgG 4 (numerous IgG positive cells).
