Inflammatory angiomyolipomas of the liver: a clinicopathologic and immunohistochemical analysis of 5 cases

Mesenchymal Tumors of the Liver: An Update Review

Hepatic mesenchymal tumors (HMTs) are non-epithelial benign and malignant tumors with or without specific mesenchymal cell differentiation. They are relatively uncommon. Except for mesenchymal hamartoma, calcified nested stromal-epithelial tumor, and embryonal sarcoma, most mesenchymal lesions are not specific to the liver. Pathologists face challenges in diagnosing HMTs due to their diverse morphologies and phenotypic variations. Accurate diagnosis is critical for directing appropriate patient care and predicting outcomes. This review focuses on mesenchymal tumors with a relative predilection for the liver, including vascular and non-vascular mesenchymal neoplasms. It provides a thorough and up-to-date overview, concentrating on clinical and pathological features, differential diagnosis, and diagnostic approaches.

A case of pancreatic PEComa with prominent inflammatory cell infiltration: the inflammatory subtype is a distinct histologic group of PEComa

BACKGROUND

PEComa is a mesenchymal tumor that can occur in various organs including the uterus and soft tissues. PEComas are composed of perivascular epithelioid cells, and angiomyolipoma (AML), clear cell sugar tumor (CCST), and lymphangiomyomatosis (LAM) are considered lesions of the same lineage as tumors of the PEComa family. Histologically, a common PEComa shows solid or sheet-like proliferation of epithelioid cells. This is accompanied by an increase in the number of dilated blood vessels. Here, we report a case of pancreatic PEComa with marked inflammatory cell infiltration.

CASE PRESENTATION

A 74-year-old male patient underwent an appendectomy for acute appendicitis. Postoperative computed tomography and magnetic resonance imaging revealed a 30 × 25 mm non-contrast-enhanced circular lesion in the tail of the pancreas. The imaging findings were consistent with a malignant tumor, and distal pancreatectomy was performed. Histologically, most area of the lesion was infiltrated with inflammatory cells. A few epithelioid cells with large, round nuclei, distinct nucleoli, and eosinophilic granular cytoplasm were observed. Spindle-shaped tumor cells were observed. Delicate and dilated blood vessels were observed around the tumor cells. Immunohistochemically, the atypical cells were positive for αSMA, Melan A, HMB-45, and TFE3. The cytological characteristics of the tumor cells and the results of immunohistochemical staining led to a diagnosis of pancreatic PEComa.

CONCLUSIONS

A histological variant known as the inflammatory subtype has been defined for hepatic AML. A small number of tumor cells present with marked inflammatory cell infiltration, accounting for more than half of the lesions, and an inflammatory myofibroblastic tumor-like appearance. To our knowledge, this is the first report of pancreatic PEComa with severe inflammation. PEComa is also a generic term for tumors derived from perivascular epithelioid cells, such as AML, CCST, and LAM. Thus, this case is considered an inflammatory subtype of PEComa. It has a distinctive morphology that is not typical of PEComa. This histological phenotype should be widely recognized.

TSC2 inactivation, low mutation burden and high macrophage infiltration characterise hepatic angiomyolipomas

AIMS

Although TSC1 or TSC2 inactivating mutations that lead to mTORC1 hyperactivation have been reported in hepatic angiomyolipomas (hAML), the role of other somatic genetic events that may contribute to hAML development is unknown. There are also limited data regarding the tumour microenvironment (TME) of hAML. The aim of the present study was to identify other somatic events in genomic level and changes in TME that contribute to tumorigenesis in hAML.

METHODS AND RESULTS

In this study, we performed exome sequencing in nine sporadic hAML tumours and deep-coverage targeted sequencing for TSC2 in three additional hAML. Immunohistochemistry and multiplex immunofluorescence were carried out for 15 proteins to characterise the tumour microenvironment and assess immune cell infiltration. Inactivating somatic variants in TSC2 were identified in 10 of 12 (83%) cases, with a median allele frequency of 13.6%. Five to 18 somatic variants (median number: nine, median allele frequency 21%) not in TSC1 or TSC2 were also identified, mostly of uncertain clinical significance. Copy number changes were rare, but detection was impaired by low tumour purity. Immunohistochemistry demonstrated numerous CD68+ macrophages of distinct appearance from Küpffer cells. Multiplex immunofluorescence revealed low numbers of exhausted PD-1+/PD-L1+, FOXP3+ and CD8+ T cells.

CONCLUSION

hAML tumours have consistent inactivating mutations in TSC2 and have a low somatic mutation rate, similar to other TSC-associated tumours. Careful histological review, standard IHC and multiplex immunofluorescence demonstrated marked infiltration by non-neoplastic inflammatory cells, mostly macrophages.

A case report of hepatic angiomyolipoma, inflammatory subtype. Clinico-pathological characterization: a diagnostic challenge

BACKGROUND

Angiomyolipoma is a benign mesenchymal neoplasm of a wide histological heterogeneity belonging to the PEComa "family." The liver, after the kidney, is their second most frequent location. However, inflammatory hepatic AMLs constitute a rare entity, with only fourteen documented cases until 2020. These neoplasms can overlap morphological features of IgG4-related diseases, being of great diagnostic relevance to demonstrating myomelanocytic-lineage differentiation of the neoplastic cells.

CASE PRESENTATION

we present a new case of an inflammatory hepatic AML resembling an IgG4-related disease in a 35-year-old woman with a subcapsular 5 cm mass confined to segment VII of the right hepatic lobe. Although having reduced its size along the tumor's natural evolution, complete tumor resection was decided due to its hypermetabolic behavior (max. SUV = 12,6) assessed by PET-CT scan. Finally, the patient underwent a right hepatectomy due to spontaneous rupture and bleeding of the lesion during the intervention. All the diagnostic and therapeutic procedures occurred in the last months of the COVID-19 pandemic.

CONCLUSIONS

This review aims to describe inflammatory hepatic AML histological and immunohistochemical features. We further sought to establish a clinicopathological contextualization of this tumoral subtype.

Primary hepatic epithelioid angiomyolipoma: a small case series

BACKGROUND

Hepatic epithelioid angiomyolipomas (HEAMLs) are rare and usually arise in case reports, and thus, we aimed to study the clinicopathological features, treatment and prognosis of these lesions.

METHODS

We identified patients from institutional database with HEAMLs and retrospectively collected clinical data.

RESULTS

Of 12 patients, 10 were females, and the median age was 49 years. A liver mass was found on chance upon routine health screening in nine patients. Imaging features included clear border (9/12), internal heterogeneity (8/12), arterial enhancement (12/12), fat (5/12), intra-tumour vessel (3/12), draining hepatic vein (2/12) and pseudocapsule (1/12). The preoperative diagnoses contained HEAML (n = 5), hepatocellular carcinoma (n = 6), and hepatic cystadenocarcinoma (n = 1). All cases had received surgery and obtained a negative margin. All specimens showed positive findings for HMB-45 and Melan A. No tumour recurrence or mortality was described with a mean follow-up time of 23.5 months.

CONCLUSIONS

HEAML is a low potential malignancy tumour that frequently appears in middle-aged females. It has nonspecific symptoms and may present special imaging features including intra-tumour vessel, early draining hepatic vein and lack of a pseudo capsule. The lesion is confirmed by pathological and immunohistochemical findings. Surgery and subsequent long-term follow-up are the most appropriate management approaches.

Clinicopathological correlation and post-resection outcomes of hepatic angiomyolipoma

Backgrounds/Aims

Angiomyolipoma is a rare neoplasm of mesenchymal origin derived from perivascular epithelioid cells. Due to rarity, hepatic angiomyolipoma (HAML) has been often misdiagnosed as hepatocellular carcinoma (HCC) or other hypervascular liver tumors based on imaging studies. This study investigated the clinicopathological correlation and post-resection outcomes of HAML.

Methods

This retrospective observational study included 40 patients who underwent hepatic resection (HR) for HAML between 2008 and 2018.

Results

Mean age of the patients was 42.6±11.4 years and there were 30 (75.0%) females. Hepatitis B and C virus infection was present in 8 patients (20.0%) and 1 patient (2.5%), respectively. Preoperative diagnoses on imaging studies were HCC in 23 (57.5%) patients, HAML in 14 (35.0%) patients, focal nodular hyperplasia in 2 (5.0%) patients, and hepatic adenoma in 1 (2.5%) patient. Percutaneous liver biopsy was performed in 10 (25.0%) patients and HAML was diagnosed in all patients. Only 3 patients (7.5%) showed a slight elevation in the level of liver tumor markers. Major HR was performed in 10 (25.0%). Laparoscopic HR was performed in 9 (22.5%). The mean tumor size was 4.8±3.9 cm and single tumor was present in 38 (95.0%) patients. Currently, all the patients are alive without tumor recurrence during the follow-up observation period of 75.7±37.3 months.

Conclusions

HAML is a rare form of primary liver tumor and is often misdiagnosed as HCC or other hypervascular tumors. Although HAML is benign in nature, it has malignant potential, thus resection is indicated if the tumor grows or malignancy cannot be excluded.

Recent Advances in Digestive Tract Tumors: Updates From the 5th Edition of the World Health Organization "Blue Book"

CONTEXT.—

The World Health Organization Classification of Tumours: Digestive System Tumors, 5th edition, was published in 2019 and shows several impactful changes as compared with the 4th edition published in 2010. Changes include a revised nomenclature of serrated lesions and revamping the classification of neuroendocrine neoplasms. Appendiceal goblet cell adenocarcinoma is heavily revised, and intrahepatic cholangiocarcinoma is split into 2 subtypes. New subtypes of colorectal carcinoma and hepatocellular carcinoma are described. Precursor lesions are emphasized with their own entries, and both dysplastic and invasive lesions are generally recommended to be graded using a 2-tier system. Hematolymphoid tumors, mesenchymal tumors, and genetic tumor syndromes each have their own sections in the 5th edition. New hematolymphoid lesions include monomorphic epitheliotropic intestinal T-cell lymphoma; duodenal-type follicular lymphoma; intestinal T-cell lymphoma, not otherwise specified; and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. This paper will provide an in-depth look at the changes in the 5th edition as compared with the 4th edition.

OBJECTIVE.—

To provide a comprehensive, in-depth update on the World Health Organization classification of digestive tumors, including changes to nomenclature, updated diagnostic criteria, and newly described entities.

DATA SOURCES.—

The 5th edition of the World Health Organization Classification of Tumours: Digestive System Tumours, as well as the 4th edition.

CONCLUSIONS.—

The World Health Organization has made many key changes in its newest update on tumors of the digestive system. Pathologists should be aware of these changes and incorporate them into their practice as able or necessary.

Paraneoplastic disorders associated with miscellaneous neoplasms with focus on selected soft tissue and Undifferentiated/ rhabdoid malignancies

A variety of soft tissue and visceral neoplasms have been associated with constitutional symptoms and signs including fever, fatigue, arthritis and laboratory abnormalities such as elevated erythrocyte sedimentation rate, leukocytosis with marked neutrophilia, anemia, thrombocytosis and others. This review addresses three main neoplastic categories that are associated with specific paraneoplastic phenomena: (1) neoplasms having in common the presence of diffuse mixed inflammatory infiltration (closely simulating an inflammatory pseudotumor) and frequently associated with constitutional symptoms; (2) neoplasms with undifferentiated, anaplastic or rhabdoid cell morphology (frequently SWI/SNF-deficient) associated with diverse paraneoplastic manifestations; and (3) paraneoplasia associated with neoplasms carrying specific gene fusions such as solitary fibrous tumor (STAT6-NAB2 gene fusions), infantile fibrosarcoma and congenital mesoblastic nephroma (ETV6-NTRK3 gene fusions), and angiomatoid fibrous histiocytoma (EWSR1-CREB1 & EWSR1-ATF1 fusions).

Angiomyolipoma of the Liver: A Rare Benign Tumor Treated with a Laparoscopic Approach for the First Time

BACKGROUND/AIM

Epithelioid angiomyolipoma of the liver is a rare benign mesenchymal tumor that usually presents in adult female patients. It most frequently occurs in the kidney, with the liver being the second most common site of involvement. Angiomyolipoma belongs to a family of tumors arising from perivascular epithelioid cells, but in rare cases may also have cystic features. We report our experience via the first case of hepatic angiomyolipoma treated by laparoscopic approach.

PATIENTS AND METHODS

We present the case of a 50-year-old female patient complaining of abdominal pain. Abdominal ultrasound (US) and Magnetic Resonance Imaging (MRI) revealed a 5 × 3 cm mass located in the left liver lobe. The tumor was resected with a laparoscopic approach. Microscopic examination of the tumor revealed hepatic angiomyolipoma.

RESULTS

Twenty-seven months postoperatively, the patient remains fit and healthy.

CONCLUSION

Angiomyolipoma can be removed by laparoscopy.

Renal myolipoosteoma: A distinctive lesion in a child

We describe a distinctive renal tumor, a myolipoosteoma (MLO), in an 11-year-old boy who presented with a 6-month history of slight right flank intermittent pain. A gross examination revealed a well-defined, 5.5 cm mass with bone-like consistency. The lesion histologically featured an admixture of mature adipose tissue, spindle cells, and bony components. No atypia, mitotic activity, or pleomorphisms were observed in the tumor. The spindle cells were smooth muscle actin (SMA) and desmin positive but HMB45 and Melan-A negative, indicating that they were of a muscular nature and differed from that of angiomyolipoma (AML). The patient had no evidence of recurrence or metastasis 56 months postoperatively. We speculate that the present tumor, which to the best of our knowledge differs from all previously described tumors, is of nephrogenic rest (NR) origin and has a favorable prognosis.

Epithelioid angiomyolipoma of the liver: Clinicopathological correlation in a series of 4 cases

Hepatic angiomyolipoma is a rare neoplasm that can be difficult to diagnose in cases of ecoguide biopsy. We studied 4 cases of female patients with a mean age of 51 years. None of the patients presented specific abdominal symptoms, or other tumour masses detected by chance. One of them had relevant personal history: Renal cell carcinoma. This same patient was diagnosed with a contralateral renal angiomyolipoma. None of the patients showed evidence of tuberous sclerosis. Three tumours have been diagnosed by biopsy and only in one patient was decided to completely remove the tumour surgically. None of the patients had evidence of recurrence of disease or an increase in tumour size over an average period of 45 months. Histologically, the tumours have been sub classified into angiomyolipomas epithelioid. In 50% of the cases, extramedullary haematopoiesis was observed. The first diagnostic impression using imaging methods included: Focal nodular hyperplasia, hepatocellular adenoma, hepatocellular carcinoma and metastasis. By immunohistochemistry, it has been demonstrated that all tumours expressing melanocytic markers (HMB45 and Melan A) and markers of smooth muscle cells (smooth muscle actin). The diagnosis of these tumours is increasing due to programmes for early detection of hepatocellular carcinoma in patients with liver cirrhosis. It must be taken into account their broad spectrum of morphological diversity to avoid incorrect diagnosis of a malignant neoplasm.

Clinico-pathological correlation of hepatic angiomyolipoma: a series of 23 resection cases

BACKGROUND

Angiomyolipomas are rare neoplasms of mesenchymal origin and are derived from perivascular epithelioid cells. They usually develop in the kidney and rarely in the liver. Due to their rarity, most hepatic angiomyolipomas have been misinterpreted as hepatocellular carcinoma (HCC) or other hypervascular liver tumours on imaging studies. We aimed to assess the clinico-pathological correlation of hepatic angiomyolipoma.

METHODS

We identified 23 patients with hepatic angiomyolipoma through an institutional database search.

RESULTS

Of 5680 cases of primary liver tumours, 23 (0.4%) had angiomyolipomas (mean age, 43.6 ± 12.4 years; 16 female patients). Hepatitis B virus infection was noted in four patients, whereas a liver mass was incidentally detected on routine health screening in 13 patients. The preoperative diagnoses, before liver biopsy, included HCC in 14, angiomyolipoma in six, focal nodular hyperplasia in two and hepatic adenoma in one patient. Eventually, the preoperative diagnoses were changed to HCC in 12 and hepatic angiomyolipoma in 11 patients. The tumour size was 5.3 ± 4.6 cm, and 22 patients had a single tumour. All tumours exhibited positive findings for human melanoma black-45 and smooth muscle actin staining. During a follow-up period of 52.2 ± 23.7 months, none of the patients exhibited tumour recurrence or mortality.

CONCLUSIONS

Hepatic angiomyolipoma is a rare form of primary liver tumour and is often misdiagnosed as other hypervascular tumours. Although angiomyolipoma is benign in nature, it also has malignant potential; hence, resection is indicated if the tumour grows or malignancy cannot be excluded. Surgical resection is a definitive curative treatment of hepatic angiomyolipoma.

Granulomatous reaction in hepatic inflammatory angiomyolipoma after chemoembolization and spontaneous rupture

A 77-year-old Japanese woman was transported to a nearby hospital due to sudden abdominal pain and transient loss of consciousness. Abdominal computed tomography (CT) suggested hemoperitoneum and hepatic nodule. She was conservatively treated. Contrast-enhanced CT two months later revealed an increased mass size, and the enhancement pattern suggested the possibility of hepatocellular carcinoma (HCC). Under a clinical diagnosis of HCC, transcatheter arterial chemoembolization (TACE) was performed. A subsequent imaging study revealed that most of the lipiodol used for the embolization was washed out. Therefore, surgical resection was performed. Histologically, the nodule contained numerous inflammatory cells including small lymphocytes, plasma cells and macrophages. Notably, epithelioid granulomatous features with multinucleated giant cells were observed in both the nodule and background liver. Some of the multinucleated giant cells contained oil lipid. Among the infiltrating inflammatory cells, spindle-shaped, histiocytoid or myoid tumor cells with eosinophilic cytoplasm were found. The tumor cells were positive for Melan A and HMB45. The nodule contained many IgG4-positive plasma cells; these were counted and found to number 72.6 cells/HPF (range: 61-80). The calculated IgG4:IgG ratio was 33.2%. The nodule was finally diagnosed as previously ruptured inflammatory angiomyolipoma modified by granulomatous reaction after TACE.

Mesenchymal Tumors of the Gastrointestinal Tract Other than GIST

Mesenchymal tumors involve the gastrointestinal (GI) tract more frequently than other visceral organs. Many such tumors are small, and are benign and increasingly being detected incidentally during colonoscopic screening. Some tumors show distinctive features at this site, such as schwannoma and clear cell sarcoma-like tumor of the GI tract. Without knowledge of these features, recognition of these tumor types can be difficult. This reviews addresses recent developments and diagnostic features of mesenchymal tumors of the GI tract other than gastrointestinal stromal tumor (GIST).

Epithelioid angiomyolipoma of liver with an inflammatory component: a case report

Angiomyolipomas (AMLs) are benign mesenchymal tumors seen in kidneys in association with tuberous sclerosis. They are uncommon in liver. Angiomyolipomas of liver show great histological diversity and various types and patterns are described. Among them, epithelioid and inflammatory angiomyolipomas are rare. We report a case of epithelioid angiomyolipoma of Liver with an inflammatory component.

Inflammatory angiomyolipoma of the liver: a rare hepatic tumor

Angiomyolipoma (AML) is a rare mesenchymal neoplasm of the tumor, composed of a varying heterogeneous mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Hepatic AML may demonstrate a marked histological diversity. We herein present one case of hepatic AML exhibiting prominent inflammatory cells in the background, which happened in a 61-year-old Chinese female patient, without signs of tuberous sclerosis. Histologically, the striking feature was the infiltration of numerous inflammatory cells in the background, including small lymphocytes, plasma cells, and eosnophils. The tumor cells were spindled and histiocytoid in shape, with slightly eosinophilic cytoplasm, and arranged along the vessels or scattered among the inflammatory background. Sinusoid structure was obviously seen in the tumor. Mature adipocytes and thick-walled blood vessels were focally observed at the boundaries between the tumor and surrounding liver tissues. The tumor cells were positive immunostaining for HMB-45, Melan-A, and smooth muscle actin. The inflammatory AML should be distinguished from other tumors with inflammatory background such as inflammatory myofibroblastic tumor and follicular dendritic cell tumor and deserves wider recognition for its occurrence as a primary hepatic tumor.

Angiogenesis and lymphangiogenesis in sporadic hepatic angiomyolipoma

Angiogenesis and lymphangiogenesis are critical processes for tumor growth, invasion, and metastasis. The present study aimed to investigate the distribution and clinical significance of angiogenesis and lymphangiogenesis in hepatic angiomyolipoma (AML). We performed immunohistochemical staining for endothelial cell markers (CD34 and podoplanin) on 80 cases of sporadic hepatic AMLs. Microvessel density (MVD) and lymphatic vessel density (LVD) were determined in intratumoral and peritumoral regions and adjacent non-tumorous liver tissues. All hepatic AMLs showed positive staining for CD34 and podoplanin. Intratumoral and peritumoral MVDs and LVDs were significantly higher than those in adjacent liver tissues (P<0.001). No statistical difference in both MVD and LVD was found between intratumoral and peritumoral areas. Large tumors (>5cm) had a significantly increased MVD and LVD as compared with smaller tumors. A significant positive correlation was found between average LVDs and MVDs (r=0.567, P<0.001), and LVDs were a relatively lower event as compared with MVDs. Double immunostaining revealed that no neoplastic cells positive for HMB-45, an antibody reacting with melanosome-associated antigen, were concurrently immunoreactive for endothelial cell markers. In conclusion, intratumoral and peritumoral angiogenesis and lymphangiogenesis commonly occur in hepatic AMLs, thus representing potential therapeutic targets for this disease.