Slit-like Vascular Spaces Research Articles

Sclerosing Angiomatoid Nodular Transformation of The Spleen: A report of a rare entity

Abstract Introduction/Objective Sclerosing angiomatoid nodular transformation (SANT) is a benign vascular lesion of spleen with uncertain etiology. It predominately affects women between 30 to 60 years of age. Clinically, it is asymptomatic or can cause abdominal pain, but usually discovered incidentally on imaging, which can identify a mass but may not provide a definitive diagnosis. In uncertain vascular lesions, there is always a risk of spontaneous rupture of large vessels and potential for spreading malignancy. Hence, the final diagnosis is rendered on microscopy after splenectomy Methods/Case Report A middle age female came to clinic complaining of abdominal pain. Radiology showed solid splenic mass and the patient underwent splenectomy. Gross examination showed a 3 cm white firm mass with focal hemorrhage. Microscopy revealed multiple nodules of variable sizes surrounded by fibrosclerotic stroma. The nodules showed round to slit-like vascular spaces with numerous red blood cells. The internodular stroma consisted of dense fibrous tissue with scattered plump myofibroblasts and lymphoplasmacytic cells. These distinctive features lead to the diagnosis of SANT Results (if a Case Study enter NA) SANT possessed characteristic histologic features with distinctive immunohistochemistry (IHC). IHC reveals three different types of vessels within the nodules: 1. Small veins (CD34- CD31+ CD8-); 2. Sinusoids (CD34- CD31+ CD8+); and 3. Capillaries (CD34+ CD31+ CD8-). All 3 vessels are negative for CD21/CD35 and CD68. Hemangioma and littoral cell angioma are two frequent vascular tumors in the spleen that should be differentiated. Both lesions lack microscopic features of SANT and have only a single type of vessels. The vessels in hemangioma are (CD31+ CD34+ CD8-); while in littoral cell angioma they are (CD31+ CD34- CD8- CD21+ CD68+) Conclusion There are no specific clinical or radiologic findings for SANT. It is important to recognize these characteristic features and to differentiate it from other benign and malignant lesions, such as angiosarcoma. A thorough histopathologic examination and IHC are helpful to make the correct diagnosis

Clinicopathologic Characterization of Kaposi Sarcoma on the Foot and Ankle: Analysis of 11 Patients Seen in Our Clinics.

Kaposi sarcoma (KS) has multiple clinical variants, and most frequently presents on the lower extremities. Anti-human immunodeficiency virus (HIV) therapy has significantly reduced the incidence of KS. However, KS is still prevalent in both HIV-infected and HIV-uninfected patients. This case series analysis aims to reveal the clinical presentations, differential diagnosis, and treatment options of KS on the foot and ankle. Eleven cases of KS involving the foot and ankle were retrieved from our patient database, and their clinicopathologic features were analyzed. All patients were men, aged 29 to 85 years. Two types of KS were found: classic and acquired immunodeficiency syndrome-associated epidemic. The average ages of classic and epidemic KS were 65.7 and 41.8 years, respectively. Clinically, three patients manifested multiple erythematous or deep violaceous, or blue-violaceous macules on either the dorsal or plantar surfaces of both feet. Eight patients showed exophytic, pyogenic granuloma-like nodules on the plantar surface, heels, and toes. Histologically, all KSs had uniform intervening fascicles of elongated spindle cells with slit-like vascular spaces filled with red blood cells and immunoreactivity with human herpesvirus-8. The patients were treated according to HIV infection status. Human immunodeficiency virus-infected patients were treated with anti-HIV therapy after primary surgical excision or biopsy. Human immunodeficiency virus-negative patients were treated with either surgical excision, Mohs surgery, or a combination of surgical excision and local radiotherapy according to individual patient clinical presentation. Kaposi sarcoma is still prevalent in both HIV-infected and HIV-uninfected patients with a variety of clinical presentations. Biopsy, with histologic evaluation, in combination with immunohistochemistry is essential for the differential diagnosis. The patient should be treated according their clinical manifestation, staging, comorbidity, and immune function.

DP19 Two patients with Kaposi sarcoma from the 2-week-wait clinic

Abstract We present two cases of Kaposi sarcoma (KS) in HIV-negative men who have sex with men (MSM) with no coexisting immunosuppressive treatment or conditions. They both presented with suspicious lesions on lower extremities, with no other mucocutaneous involvement. The initial clinical presentation of both patients was atypical, with uncharacteristic aspects of lesions on clinical examination and dermoscopy, which prompted further investigations. Skin biopsies were performed for both patients. Both cases had similar histological findings in keeping with KS: slit-like vascular spaces within the dermis, proliferation of capillary blood vessels with associated inflammatory infiltrate with lymphocytes and plasma cells and focal aggregates of spindle cells. Immunohistochemistry revealed endothelial cells displaying positive staining for human herpesvirus (HHV)-8. Immunodeficiency screening revealed no abnormalities, and repeat HIV screening was negative in both patients. These cases present an interesting occurrence of an increasingly encountered new subtype of KS seen in HIV-seronegative immunocompetent MSM. In addition to the four established variants of KS, this is an emerging variant that arises mostly in middle-aged MSM. HHV-8 has been identified as the aetiological agent in KS; indeed, the viral infection precedes the development of the disease. The fifth subtype is increasingly recognized: nonepidemic KS in MSM who are HIV-negative and have no other causes for immunodeficiency, as seen in our two cases. This subtype has been reported in the literature since the 1980s in this specific population. The clinical presentation resembles classic KS, with predominantly cutaneous involvement of the lower limbs, running a similar indolent course. There is a strong connection between HHV-8 infection and the development of KS; however, in countries where there is a low prevalence of the virus, in the general population, there is increased detection in the MSM group. Correlating the high detection rate of HHV-8 in MSM with its role in the development in KS, immunocompetent MSM are at risk of developing the condition. However, this subtype carries an overall good prognosis, with an indolent course and good response to similar therapeutic options used in the classic subtype.

Kaposi Sarcoma, a Trifecta of Pathogenic Mechanisms.

Kaposi’s sarcoma is a rare disease with four known variants: classic, epidemic, endemic and iatrogenic (transplant-related), all caused by an oncogenic virus named Human Herpes Virus 8. The viral infection in itself, along with the oncogenic properties of HHV8 and with immune system dysfunction, forms the grounds on which Kaposi’s Sarcoma may develop. Infection with HHV8 occurs through saliva via close contacts, blood, blood products, solid organ donation and, rarely, vertical transmission. Chronic inflammation and oncogenesis are promoted by a mix of viral genes that directly promote cell survival and transformation or interfere with the regular cell cycle and cell signaling (of particular note: LANA-1, v-IL6, vBCL-2, vIAP, vIRF3, vGPCR, gB, K1, K8.1, K15). The most common development sites for Kaposi’s sarcoma are the skin, mucocutaneous zones, lymph nodes and visceral organs, but it can also rarely appear in the musculoskeletal system, urinary system, endocrine organs, heart or eye. Histopathologically, spindle cell proliferation with slit-like vascular spaces, plasma cell and lymphocyte infiltrate are characteristic. The clinical presentation is heterogenic depending on the variant; some patients have indolent disease and others have aggressive disease. The treatment options include highly active antiretroviral therapy, surgery, radiation therapy, chemotherapy, and immunotherapy. A literature search was carried out using the MEDLINE/PubMed, SCOPUS and Google Scholar databases with a combination of keywords with the aim to provide critical, concise, and comprehensive insights into advances in the pathogenic mechanism of Kaposi’s sarcoma.

Erythematous, telangiectatic nodule within the melomental fold

Erythematous, telangiectatic nodule within the melomental fold

Panpancreatic Infiltration and Painless Jaundice in HIV/AIDS

A 41-year-old man with a history of poorly controlled HIV/AIDS and persistent Kaposi sarcoma (KS) despite paclitaxel treatment was admitted with jaundice. Laboratory studies revealed cholestatic liver enzymes with CA19-9 elevation. Positron emission tomography/computed tomography scan showed diffuse enhancement of the pancreas (Figure A). Endoscopic ultrasound demonstrated a panpancreatic infiltration with marked vascularity on Doppler analysis (Figure B) and biliary obstruction. Histopathology of endoscopic ultrasound–guided aspiration was diagnostic of panpancreatic KS revealing spindle/epithelioid cells separated by slitlike vascular spaces (Figure C) staining positive for CD31 and human herpesvirus-8.

ORAL KAPOSI SARCOMA: A CASE REPORT

Kaposi sarcoma (KS) is an uncommon angioproliferative endothelial neoplasm. The pathogenesis of KS is likely multifactorial, but the infection of the cells with the human herpesvirus 8 (HHV-8) and HIV infection represents a consistent etiologic factor. We report a case of KS associated with HIV infection. A 34-year-old male patient showed an asymptomatic nodular lesion on the anterior vestibular gingiva of the maxilla with purple color and slow evolution. The diagnostic hypothesis was of pyogenic granuloma. Excisional biopsy was performed, and results revealed the presence of fascicles of spindle cells and slit-like vascular spaces, which frequently contained erythrocytes. The immunohistochemical analysis showed positivity for the viral antigens of HHV-8. Thus, the histopathologic diagnosis of KS was established. After the final diagnosis, laboratory tests were performed, which revealed HIV infection. The patient died after 3 months of severe immunosuppression and pneumonia.

Angiosarcoma of the Liver: Clinicopathologic Features and Morphologic Patterns.

Angiosarcoma is a rare malignant neoplasm of the liver. The various morphologic patterns seen with angiosarcomas of the liver have not been systematically studied and their recognition remains a major diagnostic challenge. In order to provide more comprehensive data on the morphologic patterns, angiosarcomas that had been diagnosed between 1996 and 2016 at a large medical referral center were reviewed. The major growth patterns were classified as sinusoidal (non-mass forming) versus mass forming. The mass-forming cases were further subdivided into epithelioid, spindled, or vasoformative. The study identified 21 patients with primary hepatic angiosarcoma: 13 men and 8 women. The ages ranged from 26 to 89 years. Seventeen angiosarcomas were mass-forming tumors, of which 9 showed predominantly vasoformative growth. Most of these vasoformative cases (6/9) were composed of small vessels, 2 cases had slit-like vascular spaces, and one case showed a mixture of small and large vessels. There were 7 mass-forming angiosarcomas without vasoformation: 3 had an epithelioid morphology and 4 were composed primarily of spindled cells. The final mass-forming tumor showed a mixture of vasoformative and nonvasoformative areas. Four of 21 cases were non-mass forming and showed either diffuse sinusoidal infiltration (N=2) or prominent peliotic changes (N=2). Finally, 3 uncommon patterns were identified. One case showed nodules of spindle cells arranged in prominent whorls in a background of loose connective tissue with abundant inflammation. A second case arose in the setting of the Blue Rubber Bleb Nevus Syndrome and showed numerous tumor nodules with an architectural pattern that resembled infantile hemangioma, some with areas of atypia consistent with malignant transformation to angiosarcoma. The third unusual pattern showed multiple nodules of thin walled large caliber vascular proliferations, some of which showed atypia that reached the level of angiosarcoma. The results from this study indicate that the majority of hepatic angiosarcomas are mass forming (two third of cases), a pattern that is recognizable on H&E when vasoformative, but can mimic carcinoma or undifferentatied sarcomas when nonvasoformative (one third of cases). The sinusoidal patterns are particularly challenging and are frequently missed on initial review. Finally, we describe several unsual patterns of angiosarcoma. Awareness of these classic and rare morphologic patterns can help make the diagnosis of angiosarcoma.

P061 CYCLOSPORINE INDUCED KAPOSI SARCOMA IN AN IBD PATIENT: A DOWNWARD SPINDLE

Kaposi Sarcoma is an angioproliferative neoplasm found to be associated with human herpesvirus-8 (HHV8). Although this virus plays a role in the pathogenesis of the disease, in individuals who are human immunodeficiency virus (HIV) negative, it is exceedingly rare. Still, there have been documented cases of individuals developing gastrointestinal Kaposi sarcoma in the setting of immunosuppression, specifically solid organ transplant patients, and less frequently inflammatory bowel disease (IBD). We report a 24-year-old HIV-negative man with a history of ulcerative colitis (UC), psoriasis, atopic dermatitis, and alopecia aereata who was referred to the gastroenterology clinic after experiencing 12 episodes of watery non-bloody diarrhea per day and 20 lb. weight loss over the duration of one-month. Onset of watery diarrhea coincided with starting antibiotics (amoxicillin) for periodontal abscess. Patient reported that since his UC had been well-controlled for several years on cyclosporine prior to his presentation, he attributed the diarrhea and weight loss to antibiotic use. He was initially diagnosed with UC at age 15 and had previously been treated with multiple agents including adalimumab and intermittent prednisone without optimal response. Evaluation showed that he was positive for enteropathic E. coli and norovirus which was thought to be contributing to the diarrhea; he was negative for Giardia, Clostridium difficile, and stool cultures. Given his ongoing symptoms and history of UC, colonoscopy was performed which demonstrated multiple hemorrhagic nodules throughout the colon and terminal ileum. Biopsy results showed vasoformative spindle cell lesions compatible with Kaposi sarcoma that was HHV-8 positive and CMV negative in the terminal ileum and colon. CT chest/abdomen/pelvis demonstrated diffuse lymphadenopathy. He underwent right axillary lymph node biopsy which was consistent with Kaposi sarcoma. His cyclosporine and Truvada were discontinued. Oncology was consulted for further management. Since 1966, there have been only 16 cases of patients documented with IBD developing Kaposi sarcoma secondary to immunosuppressive therapy. Frequently, these patients were on prednisone or biologics with only two patients receiving cyclosporine for a brief period during the course of their therapy. Iatrogenic Kaposi sarcoma has been documented among transplant patients. We report a rare case of an individual with ulcerative colitis developing iatrogenic Kaposi sarcoma in the setting of long-term cyclosporine therapy. (A & B) H&E stained tissue sections of the colon biopsies demonstrates a vasoformative lesion composed of spindle cells with many small, poorly formed, slit-like vascular spaces involving the lamina propria and submucosa. Immunohistochemical stains demonstrate that this lesion is positive for endothelial markers CD31 (C) and CD34 (not pictured) as well as for Human Hepesvirus 8 (HHV-8) (D).

Early-onset epithelioid angiosarcoma: Diagnostic enigma, a rare case report

Epithelioid angiosarcoma (AS) is a rare vascular tumor affecting more commonly men in their seventh decade. We are reporting a case of epithelioid AS affecting a male patient in his third decade. He presented with a well-defined ulcerated plaque with an elevated border on the scalp. Histopathology showed sheets of epithelioid cells infiltrating the dermis, formation of slit-like vascular spaces, and cellular atypia. Immunohistochemistry showed positive CD31, D2-40, and FLI-1 and negative cytokeratin and epithelial membrane antigen. With these findings, a diagnosis of epithelioid AS was made. This case highlights the rare occurrence of this condition in younger age group.

Glomus Tumor of the Kidney: Case report

Abstract Introduction: Glomus tumors are rare benign mesenchymal neoplasms accounting for only 2% of all types of soft tissue tumors. Commonly located in the peripheral soft tissues, they are most frequently encountered in the subungual areas of fingers and toes, and very rarely in visceral organs due to the absence of glomus bodies. To date, 22 cases of primary renal glomus tumors have been described in the literature, of which 17 benign, with no evidence of recurrence or metastasis, three cases of malignant glomus tumor, and two cases with uncertain malignant potential. Case report: We report the 18th case of a benign glomus tumor of the kidney in a 49-year-old female patient, presenting the microscopic appearance (round, uniform cells with indistinct borders, scant finely granular eosinophilic cytoplasm, round nuclei lacking prominent nucleoli, arranged in solid sheets, accompanied by slit-like vascular spaces), the immunohistochemical profile (tumor cells showed immunoreactivity for smooth muscle actin, vimentin, as well as for CD34; they were negative for AE1/AE3, desmin, HMB-45, S-100 protein, renin, and chromogranin), and the differential diagnosis of this rare entity (juxtaglomerular tumor, angiomyolipoma, hemangioma, epithelioid leyomioma, solitary fibrous tumor, carcinoid tumor, and paraganglioma). Conclusion: Primary renal glomus tumors are rare tumors that radiologically can mimic other mesenchymal renal neoplasm. Accurate diagnosis is based on the microscopic appearance and especially the characteristic immunophenotype.

Primary Classic Kaposi's Sarcoma Confined to the Vulva in an HIV-Negative Patient.

Dear Editor: Kaposi's sarcoma (KS) is a vascular neoplasm associated with human herpesvirus-8 (HHV-8) infection that is primarily categorized into 4 different types: endemic (African), iatrogenic (associated with immuno-suppressive therapy), AIDS-associated (rapidly progressive form in HIV-infected patients), and classic. The classic type is frequently observed in elderly male patients of Mediterranean origin and Ashkenazi Jews, presenting as an indolent disease with bluish-red (hematoma-like) cutaneous macules that tend to progress only slowly both horizontally and vertically and develop into firm angiomatous plaques and nodules. The most frequently affected sites are the lower limbs and feet; extracutaneous involvement is uncommon1. The lesions of KS are rarely localized exclusively in unusual mucocutaneous areas, thus leading to frequent diagnostic errors2. To our knowledge, there are no reports of KS confined to female external genitalia not associated with HIV infection. Here, we report the first case of classic KS restricted to the vulva in an HIV-negative patient. An 85-year-old Caucasian woman presented to our clinic for evaluation of asymptomatic vulvar lesions that appeared over the last year and progressed. Physical examination showed several brownish-violaceous angiomatous nodules and slightly raised plaques on both labia majora and minora (Fig. 1). No other significant mucocutaneous lesions were observed, and there was no evidence of inguinal lymphadenopathy. Furthermore, no other signs or symptoms suggestive of HIV infection or immunosuppression were present. The patient denied other health problems and drug use. Skin biopsy from a lesion on the right labia majora was performed for histological examination. The clinical diagnosis of KS was confirmed on the basis of revealing dermal proliferation of spindle cells, slit-like vascular spaces, and extravasated red blood cells (Fig. 2A). Immunohistochemical investigation also demonstrated positivity for D2-40, CD34, and CD31 (Fig. 2B). Moreover, polymerase chain reaction assay revealed HHV-8 DNA sequences in the lesional skin tissue; positive and negative controls were also tested and yielded the expected results. HHV-8 in the lesional tissue was also detected by in situ hybridization. Serological test for HIV was negative; chest x-ray as well as abdominal and pelvic computed tomography showed no visceral lesions. The patient refused all proposed treatments for the vulvar lesions, including intralesional therapy with bleomycin, cryotherapy, and laser photocoagulation. The 6-month follow-up did not show any disease progression. Fig. 1 (A) Several brownish-violaceous angiomatous nodules and slightly raised plaques on both the labia majora and minora, (B) magnified image of the lesions on the right labia majora. Fig. 2 (A) Dermal proliferation of spindle cells, slit-like vascular spaces, and extravasated red blood cells (H&E, ×200), (B) immunohistochemical positivity for vascular marker CD31 (×100). Overall, KS restricted to the external genitalia is a very rare finding that is more frequent in men, particularly on the penis; approximately 50 cases have been reported in the English-language literature3. Meanwhile, it is very uncommon in women, with only 9 reported cases, all of which involved the vulva2,4. Most cases of KS of the external genitalia are related to HIV infection. In fact, to our knowledge, only 15 well-documented cases of primary penile KS in HIV-negative patients have been reported5, while there are no instances of KS confined to female external genitalia not associated with HIV infection. All previous cases of vulvar KS were monolesional forms, clinically presenting as a non-specific mass, nodule, papilloma, or abscess; none were initially suspected to be KS2. The present case of classic KS restricted to the vulva is of particular interest because of its more typical clinical appearance than previous cases, with multiple lesions showing an angiomatous aspect as well as onset in an HIV-negative patient; the latter finding emphasizes the need to include KS in the differential diagnosis of vulvar disorders in immunocompetent women, especially elderly women.

SARCOMA DE KAPOSI ANAPLÁSICO MIMETIZANDO ANGIOSSARCOMA

Introdução: O angiossarcoma é o tumor vascular mais frequente no contexto de linfedema crónico, entidade conhecida como síndrome de Stewart-Treves. Contudo, é sabido que o sarcoma de Kaposi se acompanha frequentemente de linfedema (por vezes antecedendo o aparecimento das lesões típicas), e que ocasionalmente a distinção entre sarcoma de Kaposi e angiossarcoma pode constituir um desafio diagnóstico.Caso clínico: Apresentamos o caso de um doente do sexo masculino, 69 anos de idade, com lesão em placa eritemato-violácea no membro superior esquerdo, sobre linfedema crónico. O estudo histológico mostrou uma proliferação de células epitelioides na derme, associada a atipia citológica e presença de fendas vasculares evocadoras de angiossarcoma. Contudo a correlação clínico-patológica associada ao exame de biologia molecular (PCR) permitiram estabelecer o diagnóstico de sarcoma de Kaposi anaplásico.Comentários: O nosso caso sublinha a dificuldade em diferenciar esta variante de sarcoma de Kaposi do angiossarcoma e o espectro de sobreposição clínica e histológica entre estas duas entidades.

Primary penile kaposi’s sarcoma in a HIV negative patient - case report

Kaposi's sarcoma (KS) to the external genitalia is extremely rare in HIV seronegative individuals. We present a 68-year-old man with multiple lesions on the penile glans, near the external meatus and coronal sulcus, that infiltrated in the distal penile shaft with a history of 12 months. Clinical examination revealed small skin superficial lesions with red violaceous aspects, two on the right flank, 1.5-2cm diameter, and one on the external retromaleolar right foot 2 cm in diameter. Histological examination of penile lesions revealed the presence of a dermal nodular proliferation of spindle cells into intersecting fascicles, with moderate cytologic atypia and hyaline globules, slit-like vascular spaces containing erythrocytes, with negative margins. Immunohistochemical profile was HHV-8, VIM, CD34, CD31, FVIII positive and Ki67 20%. At 6 months, after partial penile amputation, the patient observed small superficial red violaceous macular lesions, 0.5 cm, on the restant penile shaft. After resection the histological examination showed again KS. At 14 months follow-up, no signs of progression or local recurrence were registered. Despite the fact that primary penile KS is extremely rare, it should be always considered by clinician in the differential diagnosis of non-specific lesions in this area, even in HIV negative patients.

Fibroma of the Peroneus Longus Tendon Sheath in a Child: A Case Report

Tendon sheath fibromas are rare, benign soft-tissue tumours and usually involve tendons of the upper extremities, particularly the fingers. The most common presentation is a painless, slow-growing swelling. Tendon sheath fibromas are composed of dense fibrocollagenous stromas with scattered, spindle-shaped fibroblasts and narrow, slit-like vascular spaces. Ultrasonography and magnetic resonance imaging are useful diagnostic tools. We report on an 11-year-old boy with a fibroma involving the right peroneus longus tendon sheath.

Vascular Congenital Dermatofibrosarcoma Protuberans

We describe a case of congenital dermatofibrosarcoma protuberans (DFSP) that masqueraded as a vascular tumor both clinically and histologically. Based on the infiltrative growth pattern, presence of capillary-sized vessels, and spindle cell areas with slit-like vascular spaces and numerous thin-walled vessels at the periphery of the tumor, a kaposiform hemangioendothelioma was initially diagnosed. Strong diffuse CD34 positivity and the extension into the subcutaneous fat with a sieve-like effect prompted the fluorescence in situ hybridization analysis, which demonstrated a reciprocal t(17;22) translocation. According to our knowledge, this is the first report of a vascular histological variant of DFSP. This unique variant represents a potential pitfall for dermatopathologists and underlines the importance of cytogenetic diagnostics in unusual cases of DFSP.

Myoid angioendothelioma of the spleen mimicking metastatic disease in a patient with rectal cancer: a radiologic-pathologic correlation

Myoid angioendothelioma of the spleen is an uncommon, benign vascular tumor that is morphologically characterized by a composite of vascular spaces and stromal cells with myoid feature. Herein, we report a case of the myoid angioendothelioma of the spleen, concurrent with rectal adenocarcinoma. A 41-year-old woman presented with hematochezia for several weeks. Grossly, the rectal mass was a 2.5 × 2-cm ulcerative fungating lesion. The splenic mass was a 2.2 × 2-cm well-circumscribed lesion. Microscopically, the rectal mass was a well-differentiated adenocarcinoma that invaded into the pericolic adipose tissue. The splenic mass was composed of slit-like vascular spaces and fascicles of elongated stromal cells. Vascular endothelial cells were immunopositive for CD31, factor VIII-related antigen, and CD34 but negative for CD8. Stromal cells were immunopositive for smooth muscle actin but negative for desmin.

Tendon Sheath Fibroma in the Thigh

Tendon sheath fibromas are rare, benign soft tissue tumors that are predominantly found in the fingers, hands, and wrists of young adult men. This article describes a tendon sheath fibroma that developed in the thigh of a 70-year-old man, the only known tendon sheath fibroma to form in this location. Similar to tendon sheath fibromas that develop elsewhere, our patient's lesion presented as a painless, slow-growing soft tissue nodule. Physical examination revealed a firm, nontender mass with no other associated signs or symptoms. Although the imaging appearance of tendon sheath fibromas varies, our patient's lesion appeared dark on T1- and bright on T2-weighted magnetic resonance imaging. It was well marginated and enhanced with contrast.Histologically, tendon sheath fibromas are composed of dense fibrocollagenous stromas with scattered spindle-shaped fibroblasts and narrow slit-like vascular spaces. Most tendon sheath fibromas can be successfully removed by marginal excision, although 24% of lesions recur. No lesions have metastasized. Our patient's tendon sheath fibroma was removed by marginal excision, and the patient remained disease free 35 months postoperatively. Despite its rarity, tendon sheath fibroma should be included in the differential diagnosis of a thigh mass on physical examination or imaging, especially if it is painless, nontender, benign appearing, and present in men.

Fibroma of tendon sheath in the knee: A report of three cases and literature review

Fibroma of tendon sheath (FTS) is a rare and benign soft-tissue tumor. It is predominantly found in the fingers, hands, and wrists of young, adult males. We describe a series of three cases all presenting in the atypical knee location. We also review the literature on FTS, located both in the knee and elsewhere, looking for common clinical, imaging, and histologic patterns to help differentiate it from similar knee lesions. FTS typically presents as a painless, slow-growing, solid nodule. In the knee though, 71% of lesions present with pain/discomfort and 31% present with a palpable mass. Physical exam for knee FTS commonly reveals painful range of motion (50%), decreased range of motion (42%), and a palpable non-tender mass (33%). MRI of FTS usually reveals a well-defined soft-tissue mass, with low signal on T1, variable signal on T2, and variable enhancement. Histologically, the tumors are composed of a dense fibrocollagenous stroma with scattered spindle-shaped fibroblasts and narrow slit-like vascular spaces. Most FTS are removed by marginal excision, with 24% of lesions subsequently recurring. No lesion has ever metastasized. Despite its rarity, this lesion should be included in the differential diagnosis of a knee mass on physical exam or imaging, especially if it is painful, benign appearing, and present in a middle-aged male.

Dermoscopy of Kaposi's sarcoma: Areas exhibiting the multicoloured ‘rainbow pattern’

Kaposi's sarcoma is a vascular tumour characterized by a proliferation of spindle cells and endothelial cells to form closely arranged slit-like vascular spaces. Currently, the definitive diagnosis of Kaposi's sarcoma relies on histology. The dermoscopic features of Kaposi's sarcoma are not clearly defined in the scientific literature. We seek to evaluate the dermoscopic features of Kaposi's sarcoma and compare them with other vascular tumours. One hundred forty-one lesions from seven patients with histologically proven Kaposi's sarcoma were evaluated using polarized light dermoscopy for the presence of various dermoscopic features. Twenty patients with other vascular tumours were also examined. Dermoscopic examination revealed bluish-reddish coloration (84% of lesions), multicoloured areas showing various colours of the rainbow spectrum (36%), scaly surface (29%), and small brown globules (15%). The 'rainbow pattern' was found in six out of seven patients with Kaposi's sarcoma and was not observed in other vascular tumours. In addition, there was an absence of dermoscopic features specific for other vascular and non-vascular skin tumours, such as well-defined lacunae or structured vascular pattern, in most of the Kaposi's sarcoma lesions. The most frequent dermoscopic patterns in Kaposi's sarcoma were found to be bluish-reddish coloration, the 'rainbow pattern', and scaly surface. The rainbow pattern is a dermoscopic feature which has not been previously described. We propose that dermoscopy, as an adjunct to clinical examination, may enhance accuracy in the preoperative diagnosis of Kaposi's sarcoma.