HMB-45 Research Articles

Ileus secondary to a retroperitoneal malignant melanoma

Retroperitoneal malignant melanomas, either primary or metastatic, are rare. We present our clinical experience concerning one case with ileus secondary to a huge retroperitoneal malignant melanoma. A 77-year-old woman was admitted to the hospital due to progressive abdominal fullness and decreased appetite for 4 months. Plain films showed soft-tissue density in the left lower quadrant of the abdomen, as well as rightward displacement of the intestine. Laboratory data excluded any metabolic or septic causes of ileus. Abdominal computed tomography scan identified a huge retroperitoneal tumor with invasion of the left lower peritoneal space. The mass measured approximately 18.2 × 21.5 cm in the largest section. Immunohistochemical analysis of the tumor biopsies at minilaparotomy showed positive staining of tumor cells for S-100 protein, human melanoma black-45, and vimentin. Thus, a diagnosis of malignant melanoma with peritoneal metastases was established. This case highlights the possibility of a retroperitoneal malignant melanoma exerting a mass effect on the surrounding organs. The authors suggest that malignant melanoma should be taken into consideration as a possible differential diagnosis of retroperitoneal neoplasms.

Superficial Acral Fibromyxoma on the Second Toe

Superficial Acral Fibromyxoma on the Second Toe

Angiomyolipoma of the kidney: Clinicopathological and immunohistochemical study

OverviewAlthough angiomyolipoma (AML) is a relatively rare entity, it is the most common benign mesenchymal neoplasm of the kidney. The aim of this studyTo highlight the clinicopathological characteristics of AML and to assess the role of Human Melanoma Black-45 (HMB-45), Melan-A, smooth muscle actin (SMA), S-100 and cytokeratin in its diagnosis. Materials and methodsThe study included 15 cases of AML. Clinical and radiological data were retrieved from the archival files and all cases were subjected to a histopathological evaluation as well as immunohistochemical staining for HMB-45, Melan-A, SMA, S-100, and cytokeratin. ResultsAML was more common in females (female:male=4:1), the mean age was 53.9±6.45years. 60% of patients were symptomatic while the remaining 40% were asymptomatic. A statistically significant relationship was found between size of the tumor and the presence of the symptoms (P=0.02). Patients with tumor size less than 4cm were asymptomatic, while those with tumor size larger than 4cm had different symptoms.Thirteen cases were classic AML, while 2 cases were epithelioid AML. Classic AML demonstrated admixture of fatty tissue, thick-walled blood vessels, and smooth muscle, while epithelioid AML was composed mainly of epithelioid cells and contained no fat. HMB-45 was positive in all cases of AML (100%), Melan-A was positive in 13/15 (87%) while SMA was positive in 11/15 (73%) of AML with variable staining intensity. All cases of AML were negative for S-100 and cytokeratin. ConclusionAMLs have characteristic clinicopathological and immunohistochemical features and their recognition is crucial for proper diagnosis and treatment.

Leiomyomatoid angiomatous neuroendocrine tumor of the myometrium

Background: Only a few cases of Leiomyomatoid angiomatous neuroendocrine tumor (LANT) have been reported in the literature. Our case adds clinical, pathological, and immunohistochemical features. Objective: To investigate the clinicopathological characteristics of LANT. Material and Method: One case of LANT of the myometrium was reported in a review of literature. The morphological and immunohistochemical features were analyzed. Results: In the course of an annual health examination of a 40-year-old woman, ultrasound results revealed a mass in the myometrium, which was clinically diagnosed as uterine leiomyoma. The patient underwent hysterectomy. Histological examination demonstrated that the tumor was composed of prominent vasculature and cellular stromal around vessels. Mitotic activity was absent. Both vascular and stromal cells showed diffusely expressed CD56 and chromogranin A. Stromal cells also expressed actin, SMA, and desmin, but not CK or HMB45. The pathological diagnosis was LANT of the myometrium. Follow up reported no evidence of recurrence three months after surgery. Conclusion: LANT is a possible new disease entity. LANT is a dimorphic tumor consisting of smooth muscle and neurosecretory phenotype cells surrounding intratumoral vessels. Surgery may be the best treatment, resulting in good prognosis. Keywords: Immunohistochemistry, neuroendocrine neoplasm, pathology, uterus

Transcription Factor E3 Protein–Positive Perivascular Epithelioid Cell Tumor of the Appendix Presenting as Acute Appendicitis: A Case Report and Review of the Literature

Perivascular epithelioid cell tumors (PEComas) are a group of mesenchymal tumors that coexpress melanocytic and smooth muscle markers; their exact origin remains unknown. This group includes renal angiomyolipoma, clear cell sugar tumor, and lymphangioleiomyomatosis, although the term perivascular epithelioid cell tumors is currently used for lesions that exhibit a similar morphologic and immunohistochemical profile throughout the human body. Recently, a distinct subset of PEComas has been shown to harbor transcription factor E3 gene (TFE3) fusions. We report, for the first time, a unique case of TFE3-positive PEComa presenting as acute appendicitis in a 24-year-old woman. Microscopically, the tumor was composed of benign-appearing epithelioid cells with clear and eosinophilic cytoplasm, and arranged in nested and alveolar patterns. Immunohistochemical studies showed diffuse strong positivity for neuron-specific enolase, TFE3, and progesterone receptor and focal strong positivity for human melanoma black-45 (HMB-45) and melanocyte differentiation antigen (Melan-A) in the tumor cells. Although rare, PEComa should be included in the differential diagnosis of mesenchymal tumors of the appendix.

Primary meningeal melanocytoma of the central nervous system: report of 3 cases with literature reviews

Objective To investigate the clinical and pathological features of central nervous system primary meningeal melanocytoma.Methods Combined with Chosen literature reviews,the clinical data of three patients suffering from central nervous system primary meningeal melanocytoma was analyzed.Results Two tumors were found in the leptomeninges of the spinal cord,while one was found in the cerebellopontine.Imaging studies revealed nodal lesions.Two tumors out of the three were encapsulated black masses.Histologically,epithelioid and spindle cells with abundant cytoplasms were arranged in loose nests.No cellular pleomorphism was seen and nucleoli were evidently.Fine melaningranules were the in the cytoplasm of tumor cells in all cases.The mitotic indexes for the two cases were zero or one per 10 HPFs and the index of one case was 2 ～ 3/10 HPF.Immunnohistochemical studies of the tumors confirmed the presence of HMB45,MelanA,and S-100 proteins.The tumors in Case 1 and 2 were totally removed by operation,while the tumor in Case 2 was incompletely removed.No tumor reoccurred during the follow-up period.Conclusions Meningeal primary melanocytoma is a rare low-grade malignant tumor with certain pathology characteristics; the tumor may recur locally or transition to melanoma and should be distinguished from primary and melanoina melanomas,pigmented meningioma,and melanotic schwannoma. Key words: Central nervous system; Meninges ; Melanoma; Surgical procedures,operative ; Pathology

Melanotic Schwannoma of the Cervical Spine Progressing With Pulmonary Metastasis: Case Report

Melanotic schwannoma (MS) is an unusual variant of nerve sheath neoplasm. Only 10% of these tumors will undergo malignant degeneration, with exceedingly rare reported metastasis. We present a 32-year-old woman with a 6-month history of cervical pain and left arm progressive weakness. Neurological examination showed a left upper limb radicular pain, with pyramidal syndrome at C5 level. The magnetic resonance imaging (MRI) study highlighted an intradural extramedullary heterogeneous mass along the spinal cord at the C4–C5 level, slightly hyperintense with T1 and hypointense with T2-weighted sequences, invading the left neural foramen. The patient underwent C3–C5 laminectomy with total resection of a black tumor. In the postoperative period, a patent deficit of shoulder abduction ensued related to the nervous section. Microscopically, compactly fascicles of spindle-shaped cells with pleomorphic and hypercromatic nuclei, dark brown intracellular pigments, as well as some mitotic figures were seen. Immunohistochemical stains for S-100, Human Melanoma Black-45 (HMB-45), and vimentin were positive, with Ki-67 labelling index (LI) of 15% compatible with MS. Six months after radiotherapy she presents local recurrence and lung metastatic dissemination of the MS. She underwent left pulmonary segmentectomy, followed by chemotherapy and radiosurgery. The patient developed a febrile neutropenia and worsening of general status, and died after 3 months due to respiratory complications. MS are rare tumors with potential for local recurrence and distal metastasis. Complete surgical resection remains as the treatment of choice, once the uncommon cases with malignant progression shows low response to chemo and radiotherapy.

Primary rhabdomyosarcoma of the fallopian tube: A very rare case

Sarcomas of the fallopian tube are extremely rare malignancies, primary rhabdomyosarcoma (RMS) of the fallopian tube being exceedingly rare entity. We present here a case of primary RMS of the fallopian tube in a 72-year-old female who presented with occasional intermittent colicky abdominal pain and watery per vaginal discharge for 1.5 months. Macroscopic examination of the operated specimen of uterus and ovaries showed that the ampullary end of the right fallopian tube had a 9 cm tumor in its greatest axis. Microscopic examination revealed pleomorphic sarcoma of the right fallopian tube. Immunohistochemical examination revealed the tumor cells expressed desmin, myogenin, and smooth muscle actin (SMA); and are immunonegative for cytokeratin, epithelial membrane antigen (EMA), human melanoma black (HMB)-45, S-100 protein, and h-caldesmon; which was in favor of pleomorphic sarcoma, RMS. Considering the age, performance status of the patient and histology (RMS), adjuvant chemotherapy with single agent doxorubicin was considered.

Clinicopathologic analysis of 40 cases of ocular malignant melanoma

Objective To analyze clinical and pathological characteristics of ocular malignant melanoma.Methods The tumor tissue specimens of 40 ocular malignant melanoma patients were given HMB-45,S-100 monoclonal antibody HE and immunohistochemical staining,and the general information of patients,tumor location,histologic type and prognosis were also analyzed.Results In the 40 patients,25 cases occurred in the uvea,ocular surface tissue in 8 cases,orbital secondary tumors in 4 cases,2 cases of eyelid,lacrimal sac in 1 case.Pathological typing:shuttle A cell type in 13 cases,B 12 cases,spindle cell type mixed cell type in 10 cases,epithelial cell type in 2 cases,3 cases of other types.In 40 patients with S-100 showed strong positive.HMB-45 was strongly positive in 20 cases,moderate positive in 18 cases,weakly positive in 2 cases.All patients were followed up for 2 years,the pathological type of diffusion or rewarming rate:shuttle A cell type 7.7％(1/13),shuttle B cell type 0.0％,mixed cell type 10％(1/10),epithelial cells of type 50％(1/2),other types 33.3％(1/3),other types and epithelial type tumor proliferation rate or relapse rate were significantly higher than other pathological types(x2=12.46,P＜0.05).＜50 years age group 28 cases,aged 50 years in 12 cases,the difference between the two groups was statistically significant(x2=12.80,P＜0.05);male 22 cases,female 18 cases,the difference was not statistically significant(x2=0.80,P＞0.05).Conclusion ocular malignant melanoma occurred in uveal and ocular surface tissue,spindle cell type is the most common,other types and epithelial cell type melanomas diffusion rate or a high recurrence rate,the disease with high degree of malignancy,should pay attention to its early diagnosis and treatment. Key words: Melanoma; Pathology,clinical; Eye neoplasms

Dermatofibrosarcoma: a case report

A 37-year-old female was admitted to the hospital for an itching and painful subcutaneous nodule with ulceration on the extensor aspect of her left forearm for more than 6 months.The pain was severe,continuous and localized.Systemic and local treatment with antibiotics resulted in no obvious improvement.The lesion had gradually increased in size over the past 6 months and the ulcer had enlarged for 1 month.On examination,a hard infiltrative plaque measuring about 5.5 cm × 4.0 cm with a well-defined margin was seen on the extensor aspect of her left forearm,along with ulceration and some dirty discharge on the surface.The diagnosis of fibrosarcoma,grade Ⅱ was eventually made by a biopsy of the lesion,which revealed increased pigmentation in the basal layer,and tumor tissue was tightly adherent to the epidermis.Dermis and subcutaneous fat layer were infiltrated with various sizes of spindle cells with fine collagen fiber bundles between the cells.Obvious atypia and mitotic figures were easily observed in some of the cells.Immunohistochemical analysis showed moderately positive staining for fibronectin,but negative staining for human melanoma black-45 (HMB45),S100,smooth muscle actin (SMA),Melan-a,high molecular weight cytokeratin (HCK),CD34,CD68 or cytokeratin.Some diseases should be differentiated from this case,including dermatofibrosarcoma protuberans,cutaneous spindle cell squamous carcinoma,atypical fibroxanthoma,malignant fibrous histiocytoma,and so on.

Hepatic perivascular epithelioid cell tumor: Five case reports and literature review

Perivascular epithelioid cell tumor (PEComa) is a rare tumor. Here, we present data regarding clinical presentations, diagnoses, management, and prognosis of five cases of hepatic PEComa between January 2002 and December 2008. Ultrasonography showed hyperechoic masses in all patients. Precontrast computed tomography (CT) showed that all lesions scanned were heterogeneous in density and were heterogeneously enhanced in arterial phase images. In two cases, magnetic resonance imaging showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images. In enhanced scanning, lesions showed asymmetrical enhancement during arterial phase imaging. All tumors were composed of varying proportions of smooth muscle, adipose tissue, and thick-walled blood vessels, and showed positive immunohistochemical staining for Human Melanoma Black-45. All patients underwent hepatectomy, and there was no evidence of recurrence or metastasis during the follow-up period.

Clinical features of renal epithelioid angiomyolipoma

Objective To explore the pathological and clinical features of renal epithelioid angiomyolipoma (EAML). Methods From February 2001 to June 2010,4 cases of renal epithelioed angiomyolipoma (EAML) diagnosed in our unit were reviewed on their clinical and histopathological feathers retrospectively.The prognosis of renal EAML were evaluated according to the immunohistochemical findings.Of the 4 cases,the first case had a history of nodular sclerosis and presented a sign of hemorrage caused by the rupture of the tumor.The second case also showed a sign of hemorrage complicated with hemorrhagic shock.The third case had no symptom,but suffered from clear cell carinoma concomitantly on the other kidney.The fourth case came for consultation for his bilateral angiomyolipoma.All the 4 cases had fat composition founded in their CT scans. Results The first case was taken biopsy on the tumor of her right kidney,and lost of follow-up 6 months later.The second case undertaken radical nephrectomy,and no tumor recurrence detected after 10 months follow-up.The third case undertaken right nephron-sparing nephrectomy,and left nephron-sparing nephrectomy 6 months later.No recurrence detected during the follow-up 8 months later.Bilateral resection of the angiomyolipoma was performed on the fourth case,and a malignancy on the left kidney was deteceded 6 years later,then a radical nephrectomy was performed.But liver metastasis was founded half a year later during the follow-up.Immunohistochemcial staining of these tumors showed positive HMB45 and Melan-A but negative CK and EMA. Conclusions Renal EMAL has malignant potentiality,and the aggressiveness of it makes the close follow-up compulsive.Immunohistochemcial study is useful for diagnosis and differential diagnosis,even helpful to assess the prognosis. Key words: Renal epithelioid angiomyolipoma; Malignancy; Tuberous sclerosis

Treatment Option(s) for Pulmonary Lymphangioleiomyomatosis: Progress and Current Challenges

Pulmonary lymphangioleiomyomatosis (LAM) is a rare progressive cystic lung disease affecting primarily women of childbearing age (1, 2). LAM occurs sporadically (LAM-S) with prevalence of 2.6 per 1 million women or in 34% of women with tuberous sclerosis (TS) (LAM-TS) (3), an autosomal dominant hamartoma syndrome that occurs in 1 of 5,800 live births (2). Clinical manifestations of LAM are pneumothorax from cyst rupture, chylothorax from obstruction of lymphatics, and progressive decline of pulmonary function (1, 2). About 40% of patients with LAM-S and about 80% of patients with LAM-TS also develop in kidney an angiomyolipoma (AML), a benign tumor of smooth muscle (SM), blood vessels, and fat cells (1, 2). Pathological changes in the LAM lung are associated with growth throughout the lung parenchyma of LAM nodules that consist of SM-like spindle-shaped cells and epithelioid-like polygonal cells positive for melanocytic cell marker HMB45 (human melanoma black 45) (4, 5) (Figure 1). SM-like LAM cells show high immunoreactivity for PCNA (proliferating cell nuclear antigen), a marker of DNA synthesis and cell proliferation, compared with the epithelioid-like HMB45-positive cells (2), suggesting that SM-like LAM cells represent the proliferative component of the LAM nodules. The role of melanocyte-specific markers in LAM and whether they could be targeted therapeutically have been explored (6) and were reviewed in the January issue (7).

Pathology, ultra-structure and immunohistochemistry analysis of kidney oncocytoma

Objective To study the pathological,ultrastructural and immunohistochemical features of kidney oncocytoma (RO). Methods The clinical and histological features of 13 patients (5 men and 8 women;mean age,58 years,age 44 -78 years) with RO were observed.Immunohistochemical staining was performed on paraffin-embedded tissues with a panel of antibodies including vimentin,EMA,ckpan,CK7,CK18,E-cadherin,CD10,RCC,CD117,34βE12,HMB45,s-100 and Ki-67.Of the 13 cases,10were found incidentally during a health examination while the other three cases presented with lumbago and discomfort of the lumber.Four cases were analyzed by electron microscopy.Eleven were treated with radical nephrectomy and 2 with partial nephrectomy. Results Histologically,the tumor cells were mainly arranged in closely packed nests,aciniform or tubule with an occasional microcystic pattern in loose edematous hypocellular fibrous stroma.Tumor cells had moderate to abundant granular eosinophilic cytoplasm with a small,round and uniform nucleus containing finely and evenly dispersed chromati.However,focal nuclear atypia were observed with no mitotic activity.Immunohistochemically,all cases were diffusely positive for CK18 and showed variable immunoreactivity for E-cadherin,CD117,CD10 and CK7.Twelve cases were positive for EMA. All cases were negative for vimentin,34βE12,HMB45 and s-100.The proliferative index (Ki-67) was very low in all cases,with less than 1％ of the nuclei labeled.Electronic microscopy showed the cytoplasm had abundant mitochondria with lamellar cristae.Follow-up on 10 patients ( range from 2 to 67months) showed no recurrence or metastasis. Conclusions Tumor cells arranged in nests with loose hypocellu]ar and edematous stroma is the most important histological feature of RO.The immunohistochemical features could be helpful for both diagnosis and differential diagnosis. Key words: Kidney neoplasms; Oncocytoma; Immunohistochemistry; Differential diagnosis; Prognosis

Signet-Ring Cell Melanoma of the Gastroesophageal Junction: A Case Report and Literature Review

We report the first case, to our knowledge, of a possible primary, signet-ring cell melanoma of the gastroesophageal junction. The mass was initially diagnosed as an invasive, poorly differentiated carcinoma; however, on further review and immunohistochemical workup, the diagnosis of signet-ring cell melanoma was made. The lesion consisted of oval to round epithelioid cells undermining the gastric mucosa and infiltrating the muscularis mucosae. Tumor cells demonstrated abundant cytoplasm and eccentrically located nuclei, many with signet-ring cell morphology. The tumor cells were negative for mucin and pancytokeratin, strongly positive for S100 protein and Melan-A, and focally but strongly positive for human melanoma black-45. Diagnostic imaging failed to prove another site of melanoma, and no history of melanoma or cutaneous lesion was reported by the patient. Therefore, it was determined this was likely a primary lesion. We review the literature and previously reported cases of this rare histologic variant of melanoma.

Lymphangioleiomyomatosis of the lung with concurrent pulmonary and renal angiomyolipomata: a unique case

We present a unique autopsy case of a 61-year-old female with concurrent renal and multi-focal pulmonary angiomyolipomata (AML) in the setting of pulmonary lymphangioleiomyomatosis (LAM), and in the absence of documented tuberous sclerosis. There are no previously reported cases of pulmonary AML in the setting of LAM. The patient had undergone single lung transplantation 12 months prior to presenting with severe acute fibrinoid organising pneumonia in her donor lung. Despite full treatment she died 3 months following admission. Imaging revealed multiple tumours in the right kidney and left retroperitoneum, consistent with large angio-myolipomata. A left nephrectomy for a ‘benign tumour’ was performed 45 years previously. Limited post-mortem examination of the native lung revealed marked cystic change and two 3 mm homogenous yellow parench-ymal nodules. Histological examination showed cystic dilatation and a patchy proliferation of interstitial human melanoma black 45 (HMB45)-positive spindled cells consistent with LAM. The nodules were well-circumscribed, composed of mature adipocytes, small blood vessels and bland spindled cells with occasional epithelioid forms exhibiting positive staining with HMB45, smooth muscle actin and myosin, consistent with a diagnosis of AML. On review, these lesions were not seen on repeated antemortem imaging. This case illustrates that pulmonary lesions morphologically and immunohistochemically identical to AML can rarely co-exist with LAM and renal AML, and that they may be small, multiple and undetectable by imaging. We recommend that all lungs with known or suspected LAM be carefully examined for such lesions.

A Case of a Perivascular Epithelioid Cell Tumor Mimicking Colon Cancer

Perivascular epithelioid cell tumor (PEComa) is extremely rare, which originated from mesenchymal cells in the intestine, and composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. We report here on a case of PEComa in the sigmoid colon. A 62-year-old woman presented with hematochzia 10 days ago. Her abdominal computed tomography scan showed a 5 cm sized intraluminal fungating heterogeneously enhanced, high density mass, which infiltrated pericolic tissue surrounding the sigmoid colon. Colonoscopy showed a purple colored polypoid mass with lobulating contour in the sigmoid colon. She underwent laparoscopic anterior resection. On the histologic examination, the tumor consisted of polygonal epithelioid cells with sheet-like growth of nests, which looked like alveolar tissues in lung. The tumor cells were strongly positive stained with human melanoma black-45 (HMB-45). Pathologic examination was compatible with PEComa. Sixteen months after surgery, she did well without tumor recurrence after surgery. We review the literatures concerning PEComa of the intestine focusing on endoscopic findings.

Lymphangioma of the small bowel mesentery: A case report and review of the literature

Lymphangioma is a rare benign condition characterized by proliferation of lymphatic spaces. It is usually found in the head and neck of affected children. Lymphangioma of the small-bowel mesentery is rare, having been reported for less than 1% of all lymphangiomas. Importantly, it can cause fatal complications such as volvulus or involvement of the main branch of the mesenteric arteries, requiring emergency surgery. Moreover, the gross and histopathologic findings may resemble benign multicystic mesothelioma and lymphangiomyoma. Immunohistochemical study for factor VIII-related antigen, D2-40, calretinin and human melanoma black-45 (HMB-45) are essential for diagnosis. Factor VIII-related antigen and D2-40 are positive in lymphangioma but negative in benign multicystic mesothelioma. HMB-45 shows positive study in the smooth-muscle cells around the lymphatic spaces of the lymphangiomyoma. We report a case of small-bowel volvulus induced by mesenteric lymphangioma in a 2-year-and-9-mo-old boy who presented with rapid abdominal distension and vomiting. The abdominal computed tomography scan showed a multiseptated mass at the right lower quadrant with a whirl-like small-bowel dilatation, suggestive of a mesenteric cyst with midgut volvulus. The intraoperative findings revealed a huge, lobulated, yellowish pink, cystic mass measuring 20 cm × 20 cm × 10 cm, that was originated from the small bowel mesentery with small-bowel volvulus and small-bowel dilatation. Cut surface of the mass revealed multicystic spaces containing a milky white fluid. The patient underwent tumor removal with small-bowel resection and end-to-end anastomosis. Microscopic examination revealed that the cystic walls were lined with flat endothelial cells and comprised of smooth muscle in the walls. The flat endothelial cells were positive for factor VIII-related antigen and D2-40 but negative for calretinin. HMB-45 showed negative study in the smooth-muscle cells around the lymphatic spaces. Thus, the diagnosis was lymphangioma of the small bowel mesentery with associated small bowel volvulus.

Hepatic angiomyolipoma: diagnostic findings and management.

Angiomyolipoma (AML) is a benign mesenchymal tumor that is frequently found in the kidney and, rarely, in the liver. The natural history of hepatic AML has not been clarified, and, because of the similar patterns in imaging studies, such as ultrasonography, computed tomography, and magnetic resonance imaging, some of these tumors have been overdiagnosed as hepatocellular carcinoma in the past. With an increase in the number of case reports showing detailed imaging studies and immunohistochemical staining of the tumor with human melanoma black-45, the diagnostic accuracy is also increasing. In this paper, we focused on the role of noninvasive imaging studies and histological diagnosis showing distinctive characteristics of this tumor. In addition, because several reports have described tumor progression in terms of size, recurrence after surgical resection, metastasis to other organs, and portal thrombosis, we summarized these cases for the management and discussed the indications for the surgical treatment of this tumor.

Multiple Jejunal Myeloid Sarcomas Presenting with Intestinal Obstruction in a Non-leukemic Patient: A Case Report with Ultrastructural Observations

Myeloid sarcoma is a rare extramedullary myeloid tumor, which is frequently misdiagnosed when no evidence of leukemia is initially observed. Here, we report on a peculiar case of a 49-year-old man afflicted with multiple masses in the jejunum, the superior mesentery, and the serosa of the transverse colon, without leukemic manifestation. The tumor was composed of undifferentiated small round cells containing eosinophilic cytoplasm, which were negative for myeloperoxidase, nonspecific esterase, lysozyme, terminal deoxynucleotidyl transferase, leukocyte common antigen, CD3, CD4, CD15, CD20, CD30, CD43, CD56, CD68/PG-M1, CD79a, human melanoma black-45, c-kit, and CD34 with positivity only for CD68/KP1, CD99, and vimentin. Under electron microscopy, those cells had abundant membrane-bound cytoplasmic granules that measured 200 to 300 nm in diameter, which were consistent with granulocytic azurophilic granules. The tumor was finally diagnosed as a myeloid sarcoma. The presence of non-leukemic myeloid sarcomas showing immunonegativity for conventional myeloid-leukemic markers necessitated a diagnosis by ultrastructural observation.