Retroperitoneal leiomyomas: a clinicopathologic and immunohistochemical study of 56 cases with a comparison to retroperitoneal leiomyosarcomas

Torsed retroperitoneal leiomyomas: A case report and review of literature

BACKGROUND

Retroperitoneal leiomyomas (RLs) are rare benign tumours that can occur in the pelvic and/or abdominal parietal retroperitoneum. Once torsion occurs, it causes acute abdominal pain and can even lead to serious consequences such as gangrene, peritonitis, haemoperitoneum and shock if not identified and treated promptly. Therefore, a better understanding of the characteristics of RL torsion is needed. Here, we present a case of acute pedicle torsion of an RL in the posterior peritoneum followed by a literature review.

CASE SUMMARY

Herein, we report the case of a 42-year-old woman with RL torsion. The patient visited our hospital complaining of lower abdominal pain for 6 d. Pelvic examination revealed a tender mass superior to the uterus. Pelvic magnetic resonance imaging (MRI) revealed an anterior uterine mass, multiple uterine fibroids and slight pelvic effusion. MRI suggested the possibility of a subserosal myoma of the anterior uterine wall with degeneration. Intraoperative exploration revealed a 10 cm pedunculated mass arising from the posterior peritoneum, with the pedicle torsed two times. Pathological examination confirmed a torsed RL.

CONCLUSION

In the case of a pelvic mass complicated with acute abdomen, the possibility of torsion should be considered.

Anesthetic management of a huge retroperitoneal leiomyoma: a case report

BACKGROUND

Retroperitoneal leiomyomas are rare, with just over 100 cases reported in the literature. Perioperative management of retroperitoneal leiomyomas can be challenging due to the large tumor size and the risk of hemorrhage.

CASE PRESENTATION

We report a case of a 40-year-old Han woman with a 40-cm retroperitoneal leiomyoma. General anesthesia was performed for the surgical resection. Key flow parameters like cardiac output and stroke volume variation, as shown by the Vigileo™-FloTrac™ system, enabled the anesthesiologist to implement goal-directed fluid optimization. Acute normovolemic hemodilution and cell salvage technique were used resulting in a successful en bloc tumor resection with a 6000-mL estimated blood loss. Although the patient experienced postoperative bowel obstruction, no other significant complications were observed.

CONCLUSION

Advanced hemodynamic monitoring and modern patient blood management strategies are particularly helpful for anesthetic management of huge retroperitoneal leiomyomas.

Current management of benign retroperitoneal tumors

Benign retroperitoneal tumors (BRT) represent a rare group of heterogeneous diseases. The literature lacks high-quality evidence about the optimal management of BRT, and most of the information available takes the form of case reports or case series. The aim of this review is to provide an overview of current management strategies for adult patients with BRT. A literature search using PubMed indexed articles was conducted and BRT were classified into five different biological subgroups: 1) lipomatous tumors, 2) smooth muscle tumors, 3) peripheral nerve sheath tumors, 4) myofibroblastic tumors, and 5) others. Tumors that are primarily pelvic in origin were excluded. Despite the significant heterogeneity of the disease, several generic considerations have emerged and can be applied to the management of BRT. Specifically, the risk of misdiagnosing a BRT with another pathology such as retroperitoneal sarcoma is notable. When encountered, suspected BRT should therefore be referred to a specialized sarcoma center. Multidisciplinary tumor boards, present at these centers, have a pivotal role in managing BRT. The decision of whether to offer surgery, nonsurgical treatment or a "watch-and-wait" approach should be made after multidisciplinary discussion, depending on tumor histology. Moving forward, collaborative research efforts dedicated to BRT remain crucial in gathering evidence and knowledge to further optimize patient care.

Retroperitoneal leiomyoma located in the broad ligament: A case report

BACKGROUND

Retroperitoneal leiomyoma is a rare benign tumor. Retroperitoneal leiomyomas located in the latissimus uterine ligament are even rarer. Retroperitoneal leiomyomas have similar characteristics to uterine leiomyomas in terms of tissue, which results in confusion during diagnosis.

CASE SUMMARY

A 47-year-old female with 3 years of pain in the right lower quadrant and discovery of a pelvic mass 13 d ago underwent open abdominal exploration. In the right broad ligament, a solid mass with well circumscribed boundaries, approximately 15 cm × 10 cm × 10 cm in size was bluntly peeled off. The pathological result was a spindle cell tumor, morphologically considered to originate from smooth muscle. Immunohistochemical results supported a deep soft tissue leiomyoma.

CONCLUSION

Retroperitoneal leiomyoma is a rare benign tumor, and surgical treatment can have a good therapeutic effect.

A Rare Angioleiomyoma of the Uterine Cervix: A Case Report with Peculiar MRI Findings

Angioleiomyoma (vascular leiomyoma) of the uterine cervix is an extremely rare type of benign tumor composed of smooth muscle cells and thick-walled blood vessels. Only a few cases of cervical angioleiomyoma have been reported. Here, we present imaging, including ultrasonography, contrast-enhanced CT, MRI, and histopathological findings of a 38-year-old female with an angioleiomyoma of the uterine cervix.

Canine smooth muscle tumors: A clinicopathological study

Canine smooth muscle tumors (SMTs) commonly develop in the alimentary and female genital tracts and less frequently in soft tissue. The definition of histological criteria of malignancy is less detailed for SMTs in dogs than in humans. This study evaluated the clinicopathologic features of canine SMTs and compared the veterinary and human medical criteria of malignancy. A total of 105 canine SMTs were evaluated histologically and classified according to both veterinary and human criteria. The Ki67 labeling index was assessed in all SMTs. Estrogen receptor (ER) and progesterone receptor (PR) expression was evaluated for soft tissue SMTs. Follow-up data were available in 25 cases. SMTs were diagnosed in the female genital tract (42%), alimentary tract (22%), and soft tissue (20%). Soft tissue SMTs frequently arose in the perigenital area, pelvic cavity, and retroperitoneum. A subset of soft tissue SMTs expressed ER and/or PR, resembling the gynecologic type of soft tissue SMT in humans. SMTs were less frequently malignant when assessed with human criteria than with veterinary criteria, better reflecting their benign behavior, especially in the genital tract where human criteria tolerate a higher mitotic count for leiomyoma. Decreased differentiation was correlated with increased proliferation, necrosis, and reduced desmin expression. Mitotic count, Ki67 labeling index, and necrosis were correlated with metastases and tumor-related death. Further prognostic studies are warranted to confirm the better performance of the human criteria when assessing SMT malignancy, especially genital cases, to confirm their usefulness in ER/PR-expressing soft tissue SMTs, and to better define the most useful prognostic parameters for canine SMTs.

Radiologic-Pathologic Correlation of Primary Retroperitoneal Neoplasms

An earlier incorrect version of this article appeared in print. The online version is correct.

Large retroperitoneal leiomyoma developed from the pelvic floor to the buttocks

Retroperitoneal leiomyoma is a very rare disease, with little reported information on its origin. Herein, we report a case of a large retroperitoneal leiomyoma that developed from the pelvic floor. A 44-year-old woman had a large mass protruding outside the body from the right hip. Imaging revealed a large tumor developing from the pelvic floor to the buttocks. It was difficult to identify the place of origin. Upon preoperative biopsy, the patient was diagnosed with retroperitoneal leiomyoma. Tumor removal with abdominoperineal and partial vaginal resection was performed. Based on the histological findings of the surgical specimens, she was diagnosed with a retroperitoneal leiomyoma (gynecologic type) via immunohistochemistry, the tumor cells were positive for αSMA, desmin, estrogen receptor(ER), and progesterone receptor(PgR), but negative for myoglobin, S-100, CD34, and MIB-1.This is a case of a large retroperitoneal leiomyoma that was successfully removed via abdominoperineal and partial vaginal resection.

Solitary Fibrous Tumor of the Retroperitoneal Space

A solitary fibrous tumor develops from mesenchymal cells as a pleural neoplasm, but it is also occasionally reported in extrapleural sites. Retroperitoneal tumors are a group of neoplasms located between muscles and the fascia of the posterior abdominal wall and the parietal peritoneum. Their cytology differs from that of urinary tract organs or adrenals. This case report presents a rare solitary fibrous tumor incidentally found during an ultrasound examination. A 54-year-old male underwent urgent surgery for a tumor located in the left retroperitoneal space. The histologic examination confirmed a solitary fibrous tumor with a 5% Ki67 proliferation index, a 1 MF/10 HPF mitotic activity, and CD34-positive immunostains. A solitary fibrous tumor is a rare retroperitoneal tumor. Its symptoms and signs might resemble those of the classical triad of renal cell carcinoma, although the tumor's growth phase is typically asymptomatic. Intraoperative diagnosis of a solitary fibrous tumor strongly recommends radical excision.

Retroperitoneal leiomyoma of gynecologic type: a case report and review of the litterature

Retroperitoneal leiomyomas are rare benign tumors with smooth muscle differentiation, with only ~1001 cases reported in the English literature to date. Because of its scarcity and non-specific presentation, the preoperative diagnosis might be challenging. On histology, these neoplasms share the same macroscopic, morphological and phenotypic features with uterine leiomyoma; thus, they are referred to as leiomyoma of gynecologic type. Herein, we describe a case of a voluminous retroperitoneal leiomyoma in a 51-year-old woman with a history of total hysterectomy to raise awareness about this condition, as its differential diagnosis might be challenging.

Angioleiomyoma of the lumbo-sacral region with unusual keloid-like collagen fibers

Angioleiomyoma is a benign soft tissue tumor which usually occurs in superficial or deep soft tissues. Only rarely does this tumor occur at unusual sites, including retroperitoneum. We present a rare case of lumbo-sacral angioleiomyoma in a 54-year-old man. Apart from this unusual site, the most striking morphological feature was the presence of numerous keloid-like collagen fibers interspersed among the fascicles of the neoplastic cells. Radiological, morphological and immunohistochemical features are presented, and differential diagnosis with its potential morphological mimickers is discussed.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Retroperitoneal Well-Differentiated Liposarcoma With Uterine-Type Leiomyomatous Differentiation: A First Case Report With Literature Analysis of Soft Tissue Sarcomas With Dual Lipomatous and Low-Grade Smooth Muscle Differentiation

The occurrence of smooth muscle differentiation in a liposarcoma is a very uncommon phenomenon, even in dedifferentiated liposarcomas. In dedifferentiated liposarcomas, the leiomyosarcomatous component frequently displays high-grade cytologic features, increased mitotic activity, and tumor necrosis. Even more unusual are rare reported cases of low-grade smooth muscle differentiation in atypical lipomatous tumors/well-differentiated liposarcomas (WDLS). The current case describes a 39-year-old female with a large retroperitoneal WDLS harboring a well-demarcated mass composed of benign-appearing smooth muscle fascicles completely lacking cytologic atypia and mitotic activity. In conjunction with the immunopositivity for estrogen and progesterone receptors, the morphology of this nodule was highly reminiscent of a uterine-type leiomyoma. Of note, the lipomatous component largely displayed a lipoma-like appearance with only rare foci of mildly atypical spindle cell proliferation among the adipocytes and few fibrous septae harboring atypical stromal cells. Immunohistochemical and fluorescence in situ hybridization studies revealed MDM2 gene amplification in both the lipomatous and leiomyoma-like areas, thus confirming the diagnosis of a WDLS with smooth muscle differentiation. A literature review on the subject of sarcomas with dual adipocytic and low-grade smooth muscle differentiation provided sufficient supporting evidence to categorize the tumor as a WDLS with “leiomyomatous” differentiation. Pathologists should be aware of the occurrence of uterine-type leiomyomatous differentiation in retroperitoneal WDLS to avoid potential diagnostic errors.

An estrogen receptor-positive locally aggressive smooth muscle neoplasm of the transverse colon: A case report

RATIONALE

Extrauterine leiomyomas (LMs) in women are often positive for the estrogen receptor (ER); however, almost all extrauterine leiomyosarcomas (LMSs) are negative for ER. Invasive smooth muscle neoplasms (SMNs) of the gastrointestinal tract walls are very rare and those ER statuses have not been well studied.

PATIENT CONCERNS

A 48-year-old woman presented to our hospital with a 10 years history of recurrent severe abdominal pain and diarrhea lasting about an hour, with frequency of about twice per year. She was clinically diagnosed with a submucosal tumor (SMT) of the transverse colon and underwent a partial transverse colectomy.

DIAGNOSIS

A colonoscopy revealed a 30-mm SMT in the transverse colon. A contrast abdominal computed tomography detected a 21-mm mass with significant late phase enhancement in the transverse colon and the lesion was clinically diagnosed as an SMT. Post-operative pathology confirmed a diagnosis of ER-positive locally aggressive SMN.

INTERVENTIONS

The patient underwent laparoscopic partial transverse colectomy.

OUTCOMES

The patient received no adjuvant therapy postoperatively. The patient has remained disease-free without recurrence 13 months after the surgery.

LESSONS

This is the first case of an ER-positive invasive SMN in the gastrointestinal tract. It highlights the difficulty in classifying some gastrointestinal SMNs as either LMs or LMSs and the importance of ER status in SMNs.

Benign Smooth Muscle Tumors (Leiomyomas) of Deep Somatic Soft Tissue

Leiomyomas of deep soft tissue are extremely rare and should only be diagnosed following adherence to stringent histological criteria, namely, the absence of nuclear atypia and of coagulative tumor necrosis. Whether extremely low counts of, or even any, mitotic activity are acceptable when making a diagnosis of leiomyoma in deep soft tissue sites is controversial. The morphology and immunophenotype of smooth muscle tumors in deep soft tissue are similar to their counterparts irrespective of topography. It is interesting to note that leiomyomas of deep soft tissue (extremity and retroperitoneum) are often hyalinized/sclerosed and calcified. However, the prediction of their behavior and correct codification is dependent on thorough, meticulous search for mitoses and necrosis. Leiomyomas of deep soft tissue in the extremity should be devoid of mitoses and "significant" cytological atypia. An occasional larger, slightly pleomorphic cell in the midst of bland spindle cells, can be regarded as insignificant atypia. If any mitotic activity and several atypical cells are encountered in smooth muscle tumors of deep soft tissue of the extremity, it would be prudent to invoke the appellation of smooth muscle tumor of uncertain malignant potential and advocate wide local excision and follow-up.

Genetic heterogeneity in leiomyomas of deep soft tissue

Leiomyoma of deep soft tissue is a rare type of benign smooth muscle tumor that mostly occurs in the retroperitoneum or abdominal cavity of women, and about which very little genetic information exists. In the present study, eight leiomyomas of deep soft tissue were genetically analyzed. G-banding showed that three tumors carried rearrangements of the long arm of chromosome 12, three others had 8q rearrangements, the 7^th tumor had deletion of the long arm of chromosome 7, del(7)(q22), and the 8^th had aberrations of chromosome bands 3q21∼23 and 11q21∼22. The target genes of the 12q and 8q aberrations were HMGA2 and PLAG1, respectively. In the leiomyomas with 12q rearrangements, both HMGA2 and PLAG1 were expressed whereas in the tumors with 8q aberrations, only PLAG1 was expressed. In the cases without 12q or 8q aberrations, the expression of HMGA2 was very low and PLAG1 was expressed only in the case with del(7)(q22). All eight leiomyomas of deep soft tissue expressed MED12 but none of them had mutation in exon 2 of that gene. In two tumors with 12q rearrangements, RPSAP52 on 12q14.3 was fused with non-coding RNA (accession number XR_944195) from 14q32.2 or ZFP36L1 from14q24.1. In a tumor with inv(12), exon 3 of HMGA2 was fused to a sequence in intron 1 of the CRADD gene from 12q22. The present data together with those of our two previous studies in which the fusions KAT6B-KANSL1 and EWSR1-PBX3 were described in two retroperitoneal leiomyomas carrying a t(10;17)(q22;q21) and a t(9;22)(q33;q12) translocation, respectively, show that leiomyomas of deep soft tissue are genetically heterogenous but have marked similarities to uterine leiomyomas.

Renal Leiomyoma and Leiomyosarcoma: A Study of 57 Cases

Primary renal leiomyomas and leiomyosarcomas are rare, and there is a paucity of data regarding the pathologic features and outcomes of patients with these tumors. The objective of this study was to review a large series of renal smooth muscle tumors, in order to more fully elucidate their natural histories. Fifty-seven renal smooth muscle tumors were reviewed for various histopathologic features, and leiomyosarcomas were graded using the French Federation of Cancer Centers (FNCLCC) system. Tumor cores in tissue microarrays were evaluated for smooth muscle actin, desmin, h-caldesmon, calponin, myogenin, cytokeratin (OSCAR), CD117, Ki67, estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor 1 (WT1). Leiomyomas were selected on the basis of preexisting diagnostic criteria, which included a lack of cytologic atypia, necrosis, and mitotic activity (0 to 1 mitoses/10 hpf). These were found to have a strong predilection for women, tended to arise from the renal capsule, were small (mean size, 4.2 cm), and had a low Ki67 proliferative rate (mean 1.4%). In addition, they uniformly expressed all smooth muscle markers and were ER/PR/WT1 positive in nearly all cases. In 10 patients with clinical follow-up, none had a tumor recurrence. In contrast, leiomyosarcomas had an equal sex distribution, were larger (mean size, 9.8 cm), had significantly higher mitotic activity (mean 8.6 mitoses/10 hpf), with most being FNCLCC grade 2. Leiomyosarcomas expressed at least 1 muscle marker, higher Ki67 proliferative activity (mean 20.4%) than leiomyomas, and most were ER/PR/WT1 negative. Tumor recurrence occurred in 65% of patients, and 35% of patients died of disease. This study therefore validates existing criteria to distinguish between leiomyomas and leiomyosarcomas.

Diagnostically Challenging Spindle Cell Neoplasms of the Retroperitoneum

The diagnostic spectrum of spindle cell neoplasms arising in the retroperitoneum is wide and, in the presence of commonly shared morphologic features, it may be challenging to establish a correct diagnosis in certain cases. Beyond seemingly undifferentiated spindle cell morphology, most neoplasms may reveal distinctive adipocytic, smooth muscle or myofibroblastic or nerve sheath differentiation and show additional diagnostic clues or characteristic molecular abnormalities. Obtaining sufficient and representative biopsy material, a thorough work-up, and extensive sampling of gross specimens followed by a combined histopathologic, immunohistochemical, and, if necessary, molecular work-up of these cases is advisable so as not to miss important diagnostic and/or prognostic indicators.

[Retroperitoneal leiomyoma: report of 2 cases]

Les tumeurs bénignes du muscle lisse sont fréquentes dans le tractus gastro-intestinal et génito-urinaire, et rares au niveau rétro péritonéal. Leur prévalence parmi les tumeurs rétropéritonéales primitives a été estimée entre de 0,5 à 1,2%. Une situation qui conduit à des erreurs de diagnostic. On rapporte dans cet article deux cas de léiomyome rétropéritonéal (LRP) retrouvés chez des femmes âgées entre 47et 54 ans. L'imagerie a mis en évidence une masse rétro-péritonéale, ce qui a motivé une exérèse totale de la tumeur. L'examen anatomopathologique de la pièce opératoire a posé le diagnostic de léiomyome rétro-péritonéal. L’évolution sans récidive était bonne.

Fusion of the genes EWSR1 and PBX3 in retroperitoneal leiomyoma with t(9;22)(q33;q12)

Retroperitoneal leiomyoma is a rare benign smooth muscle tumor almost exclusively found in women and with histopathological features similar to uterine leiomyomas. The pathogenesis of retroperitoneal leiomyoma is unclear and next to nothing is known about the cytogenetics and molecular genetics of the tumor. We present here a retroperitoneal leiomyoma with a t(9;22)(q33;q12) as the sole karyotypic aberration. The translocation resulted in an EWSR1-PBX3 fusion gene in which exon 9 of EWSR1 (nucleotide 1320 accession number NM_013986 version 3) was in-frame fused to exon 5 of PBX3 (nucleotide 824 accession number NM_006195 version 5). The EWSR1-PBX3 fusion transcript codes for a 529 amino acids long chimeric EWSR1-PBX3 protein which contains the N-terminal transactivation part of EWSR1 and the homeodomain of PBX3. The present study, together with our previous finding of a retroperitoneal leiomyoma with t(10;17)(q22;q21) as the sole karyotypic aberration and a KAT6B-KANSL1 fusion gene, indicates that retroperitoneal leiomyomas may be characterized by fusion genes coding for chimeric proteins. However, cytogenetic and molecular heterogeneity exists in these tumors and it is too early to tell how many and which different pathways lead to retroperitoneal leiomyomagenesis.

Novel KAT6B-KANSL1 fusion gene identified by RNA sequencing in retroperitoneal leiomyoma with t(10;17)(q22;q21)

Retroperitoneal leiomyoma is a rare type of benign smooth muscle tumor almost exclusively found in women and with histopathological features similar to uterine leiomyomas. The pathogenesis of retroperitoneal leiomyoma is unclear and next to nothing is known about the cytogenetics and molecular genetics of the tumor. Here we present the first cytogenetically analyzed retroperitoneal leiomyoma. It had a t(10;17)(q22;q21) as the sole chromosomal abnormality. Using RNA-Sequencing and the ‘grep’ command to search the fastq files of the sequence data we found that the translocation resulted in fusion of the genes KAT6B (10q22) with KANSL1 (17q21). RT-PCR together with direct (Sanger) sequencing verified the presence of a KAT6B-KANSL1 fusion transcript. No reciprocal KANSL1-KAT6B transcript was amplified suggesting that it was either absent or unexpressed. The KAT6B-KANSL1 fusion transcript consists of exons 1 to 3 of KAT6B and exons 11 to 15 of KANSL1, is 3667 bp long, has a 1398 bp long open reading frame, and codes for a 466 amino acid residue protein. The corresponding KAT6B-KANSL1 protein contains the NEMM domain (including the linker histone H1/H5, domain H15) of KAT6B and the PEHE domain of KANSL1. The function of the fusion protein might be regulation of transcription with an affinity for chromatin (linker histone H1/H5) and interaction with the HAT domain of KAT8 (PEHE domain). The tumor expressed HMGA2 and HMGA1 even though 12q14-15 and 6p looked normal by G-banding analysis. The tumor also expressed MED12 in the absence of exon 2 mutations. Overall, the data show that the examined retroperitoneal leiomyoma resembles a subset of uterine leiomyomas in terms of histology and genetics.

Uterine Angioleiomyoma: A Rare Variant of Uterine Leiomyoma

Uterine angioleiomyoma is an extremely rare and unique variant of leiomyoma. It usually occurs in middle-aged women, who commonly present with menorrhagia, abdominal pain, or abdominal mass. The lesions are either single or multiple and manifest as submucosal, intramural, or subserosal whorled nodules. Microscopy of the individual nodule shows interlacing fascicles of spindle cells swirling around thick-walled blood vessels. Angioleiomyoma usually lacks mitotic figures, pleomorphism, or necrosis, although cases with marked nuclear atypia and multinucleated giant cells have been reported. The tumor cells are immunoreactive for smooth muscle actin, desmin, h-caldesmon, and progesterone receptor, with a low Ki-67 labeling index. Because these lesions are vascular, they may undergo spontaneous rupture and pose a life-threatening emergency, especially in pregnancy. There are no specific imaging findings; therefore, a preoperative diagnosis is extremely difficult. It is important to recognize this entity and differentiate it from a malignancy, particularly when angioleiomyoma shows significant cytologic atypia or raised cancer antigen 125 levels by thorough sampling. When required, a proper immunohistochemical panel should be used to arrive at a correct diagnosis. In this review, we discuss the current knowledge on uterine angioleiomyoma and its clinical relevance.

[A case of leiomyoma of the seminal vesicle]

Leiomyoma of the seminal vesicle is a rare tumor with only scattered reports in the literature. We report a case of leiomyoma of the seminal vesicle. A 65-year-old man presented with lower abdominal discomfort. Abdominal computed tomography scan and magnetic resonance imaging revealed a mass measuring 9.3 x 4.4 x 4.0 cm posterior to the seminal vesicle. The patient underwent ultrasound guided transrectal needle biopsy of the mass, and histological findings showed leiomyoma and no evidence of malignancy. To relieve persistent lower abdominal discomfort, the resection of the tumor was performed through a lower abdominal midline incision. The tumor was not adhered to surrounding tissue without the seminal vesicle and completely removed with a portion of the seminal vesicle. The mass weighing 115 g was histologically diagnosed as leiomyoma of the seminal vesicle with no evidence of malignancy. The symptom of lower abdominal discomfort promptly improved after the surgery, and the postoperative course was uneventful. The patient has been clinically free from the disease after three years of follow-up.

Interdigitating dendritic cell sarcoma presenting in the kidney combined with retroperitoneal leiomyosarcoma: A case report and literature review

Interdigitating dendritic cell sarcoma (IDCS) and retroperitoneal leiomyosarcoma are rare tumors. The optimal diagnosis, treatment and prognosis remain unknown. The current case report presents a 46-year-old male who exhibited with a left renal mass combined with a periprostatic mass. The patient underwent surgery twice, respectively for the resection of the two masses. The postoperative pathological examination confirmed the diagnosis of IDCS presenting in the kidney and retroperitoneal leiomyosarcoma in the pelvis. To the best of our knowledge, it is the first report of IDCS in the kidney and of the combined appearance of IDCS and retroperitoneal leiomyosarcoma in the same patient.

Smooth muscle tumors of soft tissue and non-uterine viscera: biology and prognosis

Smooth muscle tumors are here considered an essentially dichotomous group composed of benign leiomyomas and malignant leiomyosarcomas. Soft tissue smooth muscle tumors with both atypia and mitotic activity are generally diagnosed leiomyosarcomas acknowledging potential for metastasis. However, lesions exist that cannot be comfortably placed in either category, and in such cases the designation 'smooth muscle tumor of uncertain biologic potential' is appropriate. The use of this category is often necessary with limited sampling, such as needle core biopsies. Benign smooth muscle tumors include smooth muscle hamartoma and angioleiomyoma. A specific category of leiomyomas are estrogen-receptor positive ones in women. These are similar to uterine leiomyomas and can occur anywhere in the abdomen and abdominal wall. Leiomyosarcomas can occur at any site, although are more frequent in the retroperitoneum and proximal extremities. They are recognized by likeness to smooth muscle cells but can undergo pleomorphic evolution ('dedifferentiation'). Presence of smooth muscle actin is nearly uniform and desmin-positivity usual. This and the lack of KIT expression separate leiomyosarcoma from GIST, an important problem in abdominal soft tissues. EBV-associated smooth muscle tumors are a specific subcategory occurring in AIDS or post-transplant patients. These tumors can have incomplete smooth muscle differentiation but show nuclear EBER as a diagnostic feature. In contrast to many other soft tissue tumors, genetics of smooth muscle tumors are poorly understood and such diagnostic testing is not yet generally applicable in this histogenetic group. Leiomyosarcomas are known to be genetically complex, often showing 'chaotic' karyotypes including aneuploidy or polyploidy, and no recurrent tumor-specific translocations have been detected.

Giant cystic leiomyoma of the uterus occupying the retroperitoneal space

A 31-year-old nulliparous woman visited our hospital complaining of abdominal distension. Abdominal ultrasonography and computed tomography revealed a 40 × 40 × 30-cm, multilocular cystic mass extending from the upper abdomen to the pelvis. Magnetic resonance imaging (MRI) revealed a cystic tumor that was hypointense on T1-weighted images and was heterogeneously hyperintense on T2-weighted images. The final diagnosis was an 8 kg leiomyoma with cystic degeneration. Uterine leiomyomas are common benign tumors in females of reproductive age. However, subserosal leiomyomas with complete cystic degeneration of the retroperitoneal space are rare, and they are difficult to accurately diagnosis without pathological examination.

Low-grade smooth muscle tumors of the primary and the secondary mullerian system: a proposed concept of multicentricity

Some patients with bland smooth muscle tumors in the uterus have synchronous or asynchronous smooth muscle tumors in the peritoneum and/or the retroperitoneum. It is usually assumed that the uterine tumor is the primary lesion, and the extrauterine neoplasm represents its metastasis. Thus, they are designated as low-grade leiomyosarcomas because they lack the diagnostic features of a conventional spindle cell leiomyosarcoma. Nineteen such cases were retrieved from the files of the Department of Pathology at The University of Texas M.D. Anderson Cancer Center, covering a period of 18 yr. Institutional Review Board approval was obtained before the initiation of this study. In addition, 31 cases of conventional uterine leiomyosarcomas of a high grade were reviewed for comparison. Clinicopathologic features such as patients' age, tumor location, histologic features, stage, treatment, and follow-up were recorded. Immunohistochemical stains for estrogen receptor (ER), progesterone receptor (PR), p53, Ki-67, and WT-1 were performed in the initially detected tumor and the subsequent neoplasm of all cases with available material in the low-grade group and selected cases in the high-grade group. Compared with high-grade leiomyosarcomas, the low-grade group cases were found at an early age (45 vs. 52.8 yr), had a longer median time of "recurrence" (42 mo for the low-grade group vs. 12 mo for high-grade leiomyosarcomas), longer median survival (165 mo for the low-grade group vs. 41 mo for the high-grade group), and a much better overall survival (84% vs. 13%). Three (16%) patients died of disease in the low-grade group versus 27 (87%) patients in the high-grade leiomyosarcoma group. We also found a difference in the location of the extrauterine tumors. Most cases of low-grade tumors were found in the pelvis, abdomen, or retroperitoneum, whereas most high-grade leiomyosarcomas involved the lung. In the low-grade tumors, there were some differences in the immunophenotype between the uterine and the extrauterine neoplasms, but in the high-grade tumors, there were no differences in the immunohistochemistry between the primary tumor and the metastasis. In addition to these differences between the 2 groups in the age of the patients, sites of recurrences, and the immunophenotype of the uterine and extrauterine tumor, neither the uterine nor the extrauterine low-grade lesions had histologic features of malignancy. On the basis of these differences, the possibility that the extrauterine lesions in the low-grade group represent independent primaries involving the secondary mullerian system is proposed.

A rare case of retroperitoneal leiomyoma

Introduction. Leiomyoma uteri is one of the most common benign conditions for which women undergo hysterectomy every year. Fibroids found retroperitoneally are a rare entity, especially, primary retroperitoneal fibroid. Case Presentation. We report a case of 42-year-old para 1 who presented to our hospital with recurring retention of urine, lower abdominal and pelvic pain, and dyspareunia . Provisional diagnosis on the basis of examination and imaging was large subserosal fibroid with mild right-sided hydroureteronephrosis, due to pressure effect of the fibroid. Abdominal hysterectomy was done for the patient, and intraoperatively, a bulky uterus was found with multiple small fibroids on anterior and posterior walls, and a large fibroid approx. 10 × 8 cm was found arising from the posterior surface at the level of internal os retroperitoneally, which was confirmed by histopathology as leiomyoma. Conclusion. Retroperitoneal fibroids are rare neoplasms and treatment is surgical removal. Preoperative imaging can only give provisional diagnosis and can be misguiding. Final diagnosis of retroperitoneal fibroid can be made only intraoperatively.

Gastrointestinal stromal tumours can express CD10 and epithelial membrane antigen but not oestrogen receptor or HMB45

AIMS

Gastrointestinal stromal tumour (GIST) may share morphological and/or immunohistochemical features with various intra-abdominal neoplasms, including endometrial stromal sarcoma, perivascular epithelioid cell tumour (PEComa), melanoma and synovial sarcoma. Each of these various neoplasms has characteristic immunohistochemical markers, including epithelial membrane antigen (EMA), CD10, oestrogen receptor alpha (ERa) and/or HMB45, and therefore the primary aim of this study was to determine whether these markers are also expressed by GISTs.

METHODS AND RESULTS

Standard size sections of 52 GISTs were immunostained for EMA, CD10, ERa and a melanoma marker cocktail (targeting HMB45 and melan-A). Ten GISTs (19%) showed CD10 immunopositivity. This positivity was confined almost completely to small intestinal GISTs, and was seen among spindle cell GISTs but not epithelioid or mixed cell-type GISTs. Five of the 52 GISTs (9.6%) showed EMA immunopositivity. This positivity was always focal and usually seen in a perivascular location. None of the GISTs showed immunopositivity for ERa or the melanoma marker cocktail.

CONCLUSIONS

GISTs occasionally show CD10 immunopositivity (especially small intestinal spindle cell GISTs), and infrequently show focal EMA positivity. GISTs do not show immunopositivity for ERa or HMB45.

Classification, molecular characterization, and the significance of pten alteration in leiomyosarcoma

Leiomyosarcoma is a malignant smooth muscle neoplasm with a complicated histopathologic classification scheme and marked differences in clinical behavior depending on the anatomic site of origin. Overlapping morphologic features of benign and borderline malignant smooth muscle neoplasms further complicate the diagnostic process. Likewise, deciphering the complex and heterogeneous patterns of genetic changes which occur in this cancer has been challenging. Preliminary studies suggest that reproducible molecular classification may be possible in the near future and new prognostic markers are emerging. Robust recapitulation of leiomyosarcoma in mice with conditional deletion of Pten in smooth muscle and the simultaneous discovery of a novel role for Pten in genomic stability provide a fresh perspective on the mechanism of leiomyosarcomagenesis and promise for therapeutic intervention.

Spindle Cell Sarcomas

Information is presented on the pathology of spindle cell sarcomas. Synovial sarcoma, malignant peripheral nerve sheath tumor, fibrosarcoma, inflammatory myofibroblastic tumor, low-grade myofibrosarcoma, leiomyosarcoma, spindle cell rhabdomyosarcoma, and endothelial neoplasms are discussed in terms of an overview of the tumor, microscopic and gross features, diagnostic techniques, genetic markers, differential diagnosis, clinical details, and prognosis.

Gastrointestinal Tract Mesenchymal Lesions

This article reviews the most common and characteristic mesenchymal lesions found in the gastrointestinal tract and intraabdominal location in a pattern-based approach: spindle and epithelioid tumors (gastrointestinal stromal tumor, schwannoma, glomus tumor, leiomyoma and leiomyosarcoma, inflammatory fibroid polyp, perineurioma, melanoma, calcifying fibrous tumor, sclerosing mesenteritis, mesenteric fibromatosis, and inflammatory myofibroblastic tumor), and clear and granular tumors (clear cell sarcoma, granular cell tumor, gangliocytic paraganglioma, and ganglioneuroma). Information includes gross and histologic features, diagnosis and differential diagnosis, and histologic and other diagnostic techniques, including immunohistochemistry related to projected patient outcome, along with prognosis, staging, and treatment.

Gastrointestinal stromal tumours--an update for histopathologists

This review aims to summarize recent knowledge gained about gastrointestinal stromal tumour (GIST) of particular relevance to histopathologists. KIT and PDGFRA mutation analyses can be useful for confirming a diagnosis of GIST, but there are some diagnostic limitations to these analyses, and so immunohistochemical markers currently remain crucial to the diagnostic process. Of these markers, CD117 and Discovered on GIST 1 (DOG1) are currently the most sensitive and specific markers of GIST, and recent data appear to disprove the fear that antigen retrieval causes false-positive CD117 immunostaining. The accurate prognostication of GIST has been greatly helped by the National Institutes of Health (NIH) and Armed Forces Institute of Pathology (AFIP) classification systems, although both systems still have limitations, and the behaviours of certain GIST subgroups are less well predicted by both systems. KIT and PDGFRA mutation analyses can help to predict the response of GISTs to receptor tyrosine kinase inhibitors, and both GISTs that respond and those that show resistance to these inhibitors may show characteristic pathological changes. Some GIST subgroups (e.g. Carney syndrome and paediatric GISTs) have had recently described clinicopathological and/or molecular characteristics which may help with the diagnosis and/or treatment of these specific neoplasms.

Retroperitoneal smooth muscle tumor of uncertain malignant potential after hysterectomy: a case report

Introduction

Smooth muscle tumors of uncertain malignant potential represent a histologically heterogeneous group of uterine smooth muscle tumors that cannot be diagnosed as either benign or malignant. Smooth muscle tumors of uncertain malignant potential are usually clinically benign, but should be considered tumors of low malignant potential because they can occasionally recur or metastasize to distant sites.

Case presentation

We report the case of a 62-year-old Mongol woman diagnosed with a retroperitoneal smooth muscle tumor of uncertain malignant potential and lung metastasis, with a history of prior hysterectomy. The case was initially misdiagnosed as retroperitoneal sarcoma, and our patient received chemotherapy. However, no interval change in the size of the retroperitoneal mass and metastatic lung nodules was seen over a period of at least five years. She underwent partial resection of the retroperitoneal mass for the purposes of debulking and establishing a histopathological diagnosis. The diagnosis of the retroperitoneal mass was then confirmed as a smooth muscle tumor of uncertain malignant potential.

Conclusion

Smooth muscle tumors of uncertain malignant potential have an unpredictable clinical course, and relapses generally appear to occur after a long disease-free interval of up to several years. Therefore, patients diagnosed with smooth muscle tumors of uncertain malignant potential should receive long-term follow-up.

Primary sarcoma of the specialised prostatic stroma: a case report and review of the literature

Primary sarcoma tumours of the prostate are rare and are classified, according to their histology, as stromal tumours of uncertain malignant potential (STUMP) and stromal prostatic sarcoma (PS; low and high grade). We describe a case of a 71-year-old man that developed progressive urinary obstruction symptoms and was subjected to a transurethral prostatic resection (TURP). Histologically, there is a diffuse proliferation of epithelioid and spindle cells that showed rare atypical mitotic figures. Immunohistochemically, the neoplastic cells express diffusely CD34 and focally progesterone whereas no immunoreactivity was seen for cytocheratin, desmin, S-100, Bcl-2, chromogranin, CD117, and actin smooth muscle. A final diagnosis of low-grade prostatic stromal sarcoma (LG-PS) was made. This is a really rare neoplasm; in the literature, in fact, to our knowledge, only 6 cases are described and all of these were alive and free of disease at followup. Our patient too is free of disease at 15 months from the diagnosis.

Pelvic retroperitoneal leiomyoma

Primary retroperitoneal leiomyomas are a rare and unusual differential diagnosis in the acute abdomen. A 26-year-old woman presented with chronic constipation and acute abdominal pain. The diagnostic workup included contrast computer tomography, transabdominal ultrasonography, and colonoscopy that revealed an 8-cm homogeneous pelvic tumor with rectal compression. Retroperitoneal leiomyoma was suspected on imaging studies and finally confirmed after tumor excision and immunohistochemical staining.

Cluster analysis of immunohistochemical markers in leiomyosarcoma delineates specific anatomic and gender subgroups

BACKGROUND

Leiomyosarcoma (LMS) can be categorized into uterine, retroperitoneal, nonretroperitoneal soft tissue, cutaneous, visceral, and osseous anatomic subtypes. The differential expression of smooth muscle markers, estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor-1 protein (WT1) by anatomic subtype and gender was explored.

METHODS

A total of 78 LMS comprised of 30 uterine and 48 nonuterine tumors were studied. Nonuterine tumors were comprised of 17 soft tissue, 16 retroperitoneal, 7 cutaneous, 5 visceral, and 3 osseous subtypes. Immunohistochemical staining intensity on tissue microarray slides was scored as 0, 1+, or 2+, and cluster analysis was performed on the data.

RESULTS

Smooth muscle actin was the most sensitive antibody (95%), followed by muscle-specific actin (91%), calponin (88%), desmin (73%), caldesmon (66%), and myosin (64%). Caldesmon and myosin were usually coexpressed, and were highest in retroperitoneal tumors (94%). There was no discernable correlation noted between histologic differentiation and smooth muscle marker expression. ER was much more common in women, with the highest frequencies noted in female retroperitoneal (86%) and uterine (63%) tumors. Nuclear WT1 was expressed in 11% of all tumors, and was limited to ER-positive uterine and female retroperitoneal tumors. Cluster analysis segregated 4 groups, most notably 1 driven by ER and PR, with the vast majority being uterine and female retroperitoneal tumors.

CONCLUSIONS

Smooth muscle markers demonstrated variable sensitivities in LMS, with a tendency for anatomic subtypes to segregate based on expression patterns of these markers. ER defined a subgroup of uterine and female retroperitoneal tumors, and WT1 was limited to such tumors, suggesting a common line of differentiation as well as potential therapeutic targets.

Retroperitoneal leiomyomata as a cause of bilateral hydronephrosis and lumbosciatic pain

Leiomyomas can occasionally be found in the pelvic and/or abdominal parietal retroperitoneum. This rare entity is known as retroperitoneal leiomyomata. We report the case of a 46-year-old female with bilateral hydronephrosis and chronic sciatic pain caused by invasive retroperitoneal leiomyoma 3 years after hysterectomy, and a successful outcome after treatment with surgery followed by aromatase inhibitors to control pelvic residual disease. Aromatase inhibitors could be a satisfactory treatment option after surgery to control retroperitoneal leiomyoma residual disease.