Fibrohistiocytic Variant of Hepatic Pseudotumor: An Antibiotic Responsive Tumefactive Lesion

Hepatic Inflammatory Pseudotumor-Focusing on Its Heterogeneity

Hepatic inflammatory pseudotumors (IPTs) are defined as benign, non-malignant, non-metastasizing tumors characterized by the presence of myofibroblastic spindle cells, hetorogenous populations of inflammatory cells, particularly plasma cells, lymphocytes and macrophages, as well as locations of fibrosis and necrosis without cellular anaplasia or atypical mitoses. Despite subsequent reports in the references, hepatic IPT remains difficult to diagnose; while posing major issues specifically for its differential diagnosis compared with that of other various benign diseases and malignant hepatic tumors. Histopathological findings are always a requisite for confirming the diagnosis, particularly given that the pathogenesis of IPT remains ambiguous to date. Hepatic IPT is a heterogeneous entity in terms of its clinical features, pathological findings, and pathogenesis. Once the diagnosis is confirmed, however, needless surgery such as wedge resection and lobectomy should be avoided. Here, we discuss the heterogeneity of hepatic IPT, its clinical features, pathological findings, and pathogenesis, and describe its differential diagnosis.

Mesenchymal Neoplasms of the Liver

Mesenchymal neoplasms of the liver can be diagnostically challenging, particularly on core needle biopsies. Here, I discuss recent updates in neoplasms that are specific to the liver (mesenchymal hamartoma, undifferentiated embryonal sarcoma, calcifying nested stromal-epithelial tumor), vascular tumors of the liver (anastomosing hemangioma, hepatic small vessel neoplasm, epithelioid hemangioendothelioma, angiosarcoma), and other tumor types that can occur primarily in the liver (PEComa/angiomyolipoma, inflammatory pseudotumor-like follicular dendritic cell sarcoma, EBV-associated smooth muscle tumor, inflammatory myofibroblastic tumor, malignant rhabdoid tumor). Lastly, I discuss metastatic sarcomas to the liver, as well as pitfalls presented by metastatic melanoma and sarcomatoid carcinoma.

Inflammatory Pseudotumor of the Liver

Hepatic inflammatory pseudotumor (IPT) describes a mass lesion composed of fibroblasts or myofibroblasts with a dense inflammatory infiltrate comprising lymphocyte, plasma cells, and histiocytes. These lesions are presumed to be an exuberant response to an infectious organism, although in most cases the causative agent is unknown. In specific circumstances, pathologists should consider ancillary techniques to exclude specific infections, such as mycobacteria, Candida, or syphilis. IgG4-related disease may cause a plasma-cell rich IPT. Finally, true neoplasms can mimic IPTs and must be excluded with appropriate ancillary studies, including inflammatory myofibroblastic tumor, follicular dendritic cell tumor, inflammatory angiomyolipoma, Hodgkin lymphoma, and inflammatory hepatocellular carcinoma.

Laparoscopic treatment of inflammatory myofibroblastic tumor in liver: A case report

BACKGROUND

Inflammatory myofibroblastic tumor in the liver (IMTL) is a rare borderline mesenchymal tumor. Neither clinical symptoms nor laboratory tests have absolute specificity for the diagnosis of IMTL, and imaging also lacks obvious specificity. Although there are sporadic reports of recurrence after surgical treatment, surgical resection is the mainstay of treatment.

CASE SUMMARY

A 29-year-old man complained of general weakness, slight discomfort in the upper abdomen, with a history of upper respiratory tract infection for 1 wk before admission. Plain and enhanced upper abdominal magnetic resonance imaging showed a mass in liver segments II and III (48 mm × 53 mm). He was treated by laparoscopic left lateral segmentectomy. Postoperative pathological examination with hematoxylin and eosin staining suggested that the mass in liver segments II and III was IMTL. During 21 mo postoperative follow-up, no obvious residual or recurrent lesions were observed.

CONCLUSION

There is a risk of malignant degeneration in IMTL. The principal choice of treatment is laparoscopic left lateral segmentectomy.