Concomitant Autoimmune Liver Disease and Hepatic Actinomycosis: A Diagnostic Challenge-Brief Report and Review of the Literature

Abstract

Hepatic actinomycosis (HA) and IgG4-related inflammatory pseudotumors are rare and often overlooked causes of liver mass, which can easily be misdiagnosed as primary liver cancer or metastasis. Diagnosis is arduous due to unspecified clinical and radiological features and the fact that histology is not always conclusive. In cases of actinomycosis, the use of molecular diagnostic techniques-such as polymerase chain reaction (PCR) for bacterial DNA-can aid in establishing a definitive diagnosis, especially when conventional cultures are non-diagnostic. We present a case report of one of our patients who was incidentally diagnosed with a hepatic lesion presenting aspecific radiological features. Since radiological imaging was inconclusive, a biopsy was performed, and a diagnosis of IgG4 related hepatic inflammatory pseudotumor was then made. Because of the disease progression, during immunosuppressive therapy, our diagnosis was questioned and a new liver biopsy was carried out. At the end, it took three consequent biopsies to finally find out the presence of an actinomyces infection.

Keywords: Actinomyces species; IgG4-related autoimmune liver disease; actinomycosis; liver mass; molecular techniques.

Figure 1

In this figure, the radiological and histological characteristics of actinomycosis are presented. (a): MRI Cross-section: lesion with irregular margins and non-homogeneously signal in T1. (Display Field of view (DFOV): 136 × 56.6 cm; native zoom 1×; spatial resolution: ~2.66 mm/pixel). (b): MRI cross-section: lesion with a hypointense core and hyperintense edges in T2. (DFOV: 114 × 47.2 cm; native zoom 1×; spatial resolution: ~2.23 mm/pixel). (c): IGG4 expression (immunohistochemical analysis, 20×). (d): cell aggregates of Actinomyces (PAS staining, 40×). (e): cell aggregates of Actinomyces (standard hematoxylin-eosin staining, 20×). (f): cell aggregates of Actinomyces (PAS, 40×).