Hobnail hemangioma: a pseudomalignant vascular lesion with a reappraisal of targetoid hemosiderotic hemangioma

Benign and low-grade superficial endothelial cell neoplasms in the molecular era

Vascular tumors are the most common mesenchymal neoplasms of the skin and subcutis, and they encompass a heterogeneous group with diverse clinical, histological, and molecular features, as well as biological behavior. Over the past two decades, molecular studies have enabled the identification of pathogenic recurrent genetic alterations that can be used as additional data points to support the correct classification of these lesions. The purpose of this review is to summarize the available data related to superficially located benign and low-grade vascular neoplasms and to highlight recent molecular advances with the role of surrogate immunohistochemistry to target pathogenic proteins as diagnostic biomarkers.

The contribution of Juan Rosai to the pathology of soft tissue tumors

The conceptual evolution in the field of soft tissue tumor pathology has been mostly driven by a relatively small group of individuals that includes giants of the past and the present such as James Ewing, Raffaele Lattes, Arthur Purdy Stout, Franz Enzinger, Sharon Weiss, Lennart Angervall, Harry Evans, Marku Miettinen, and Christopher Fletcher. Juan Rosai, not only exerted an immense impact on surgical pathology in general, but in consideration of his unique talent in identifying novel clinicopathologic entities, has also contributed remarkably to current understanding of mesenchymal neoplasms. The creation of desmoplastic small round cell tumor certainly ranks among his most relevant efforts, although he actually put his mark on a broad variety of soft tissue lesions, including vascular neoplasms. It would be impossible to include in a single article all the entities that he created or contributed to refine; therefore, this review is limited to a selection of what we believe represent true milestones.

Orbital Hobnail Hemangioma

A 64-year-old woman presented with a 1 year history of progressive left proptosis and "blurry vision." Imaging studies revealed a left superior orbital mass distorting the optic nerve and superior rectus muscle. Excisional biopsy established the diagnosis of hobnail hemangioma. This report describes the first case of an orbital hobnail hemangioma, a lesion that more commonly presents in the dermis.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Arborizing vessels in a targetoid hemosiderotic hemangioma: mistaken dermoscopic diagnosis of basal cell carcinoma

Targetoid hemosiderotic hemangioma (THH) or hobnail hemangioma (HH) is a benign vascular lesion that presents with the classical clinical presentation of a ring-shaped tumor having a targetoid appearance, with a central purple-brown papule surrounded by a thin pale area and an ecchymotic ring on the outside. Dermoscopic features and patterns of HH have been documented and have proven to be sufficient to establish a clinical diagnosis in many cases.

We present a facial lesion in which both the clinical presentation and dermoscopy were atypical. The presence of arborizing vessels in the dermoscopic pattern, never before described for this lesion, led us to the diagnosis of basocellular carcinoma (BCC). We also report the changes in this pattern experienced over 12 months of progression and their correlation with the histopathologic findings.

Hobnail Hemangioma With an Unusual Clinical Presentation

Hobnail hemangioma, also known as targetoid hemosiderotic hemangioma, is an uncommon vascular proliferation that clinically presents as a small solitary red to purple papule or macule, located on the limbs or trunk. Multiple lesions and atypical locations have been described. Histopathologically, it exhibits a biphasic pattern, with dilated vessels in the superficial dermis and angulated vessels in the deeper dermis, with endothelial cells that show a hobnail appearance. There is controversy about the histogenetic origin of hobnail hemangioma, although recent studies support that it is a lymphatic malformation. The investigators report the case of a 41-year-old man with an irregular lesion, red to purple in color, with a maximum diameter of 4 cm, on the scalp. The location and in particular the clinical appearance are uncommon. Immunohistochemical analysis showed negativity for WT1 and focal positivity for D2-40. Clinical-pathologic correlation acquires particular importance in the case of lesions with atypical clinical presentation.

Contributions of Dr. Juan Rosai to the pathology of cutaneous vascular proliferations: A review of selected lesions

Vascular proliferations in the skin have been thoroughly studied over the past 35 years, and a great deal of knowledge has been accrued regarding their pathobiological features. Dr. Juan Rosai has been a consistent contributor to the literature on this topic throughout most of his career, and this article reviews selected cutaneous endothelial lesions that he helped to characterize. They include histiocytoid-epithelioid hemangioma, targetoid-hobnail hemangioma, acquired tufted hemangioma, glomeruloid hemangioma, spindle cell hemangioma, retiform hemangioendothelioma, and angiosarcoma. Two potential simulants of angiosarcoma-papillary intravascular endothelial hyperplasia and cutaneous rudimentary meningocele-meningothelial hamartoma-are also considered.

A case report of retiform hemangioendothelioma as pleural nodules with literature review

Retiform hemangioendothelioma (RH) is a rare low-grade variant of angiosarcoma mostly reported on dermis or subcutaneously. A 30-year-old woman suffering from dry cough, dyspnea and pleural effusion has been described. Distinctive symptoms and lesions on high resolution computed tomography (HRCT) scan and common histological, immunological feature are discussed. Diagnosis was made by thoracoscopy as RH.

Hobnail Hemangioma (Superficial Hemosiderotic Lymphovascular Malformation) in Children: A Series of 6 Pediatric Cases and Review of the Literature

BACKGROUND

Hobnail hemangioma is a small benign vascular malformation of the superficial and mid-dermis with variable clinical presentation.

OBJECTIVES

To review the clinical characteristics of hobnail hemangioma in pediatric patients.

METHODS

A retrospective chart review performed of all histopathologically confirmed cases of hobnail hemangioma from May 2000 to December 2014. Data on demographics, clinical characteristics, and results of immunohistochemical staining were collected.

RESULTS

Four male and 2 female patients identified. Congenital lesions were reported in 3 cases. The most common anatomic location was the extremities. Treatment options included observation and surgical excision.

CONCLUSIONS

Hobnail hemangioma is an uncommon benign vascular malformation. Due to its benign nature, treatment is not required. If treatment is indicated, complete surgical excision appears to be the most effective option.

Hobnail Hemangioma: A Case Report

Hobnail hemangioma is a small, solitary, benign vascular tumor that shows a biphasic histological pattern of dilated vascular spaces in the superficial dermis and narrow vascular structures in the deeper dermis. In the superficial dermis, dilated, irregular, thin-walled vascular spaces are lined by plump endothelial cells with large nuclei which protrude into the lumina like hobnails. A 43-year-old Japanese man presented with an 11×8-mm bluish-red macule surrounding a 6×3-mm violaceous, slightly elevated papule of the lumbar region of 6 months' duration. Total resection was performed under local anesthesia. Microscopic examination revealed a biphasic pattern with dilated superficial vessels whose endothelial cells were plump with intraluminal papillary projections, showing a "hobnail" appearance, in the papillary layer and upper dermis, and vascular spaces forming slitlike spaces, some of them dissecting collagen fibers, in the deeper dermis. Neither true atypia nor mitotic figures were present. The findings were consistent with those of hobnail hemangioma. Immunohistochemical analysis of the endothelia of the superficial vessels showed that CD31 and D2-40 were expressed, factor VIII was focally expressed, and CD34 and α-SMA were not expressed. In the endothelia of the deeper vessels, CD31, CD34, factor VIII, and α-SMA were expressed, but D2-40 was not expressed. These findings suggest that hobnail hemangioma also shows a biphasic immunohistochemical pattern because of its origin from both lymphatic vessels and blood vessels.

Targetoid hemosiderotic hemangioma - Case report

Targetoid Hemosiderotic Hemangioma, also known as Hobnail Hemangioma, is a lesion of vascular origin, probably lymphatic. The most common clinical feature is a solitary violaceous papule surrounded by a pale, thin area and a peripheral ecchymotic ring, simulating a target. Histopathologically, there is a biphasic pattern, with dilated vessels in the superficial dermis and pseudoangiosarcomatous pattern in the deep dermis, and endothelial cells with hobnail morphology. A simple excision is curative. We report a rare case of Targetoid Hemosiderotic Hemangioma.

Superficial hemosiderotic lymphovascular malformation (hobnail hemangioma): a report of six cases

Hobnail hemangioma (HH), initially termed targetoid hemosiderotic hemangioma, is a rare, often solitary lesion classically characterized by a central brown or violaceous papulonodule surrounded at times by an ecchymotic halo. This lesion is typically found on the trunk or limbs of children or young to middle-aged adults. Numerous case reports have found HHs to have a reproducible histologic appearance. Although the exact histogenesis of these lesions is unknown, multiple recent immunohistochemical studies suggest a lymphatic origin of these lesions. We present six cases of children with HHs with classic histology but with variability in their clinical appearance. Because the clinical presence of a targetoid halo is inconsistent and the hobnail phenomenon is not specific, we favor the designation of superficial hemosiderotic lymphovascular malformation instead of HH or targetoid hemosiderotic hemangioma as a more unifying term for this rare clinical entity. By eliminating confounding terminologies (in this case, incorporation of "hemangioma" in the name of this entity), we also hope to encourage a swifter change in practice to move away from erroneous diagnostic considerations.

Congenital and multiple hobnail hemangiomas

Hobnail hemangioma (targetoid hemosiderotic hemangioma) is a vascular tumor affecting the limbs or trunk. Characteristically, the lesion has a "targetoid" clinical feature and dilated vascular spaces lined by hobnail endothelial cells at histologic examination. The age of onset is widely variable, form 5~67 years, typically occurring in young or middle-aged persons. It is usually apparent as a small solitary lesion. However, multiple lesions are identified sometimes. Herein, we report two cases of hobnail hemangioma in 7-year-old and 15-year-old males. Of note, the former case had a congenital lesion and the latter, multiple acquired lesions, which are both rare atypical presentations of the disease.

A cutaneous vascular neoplasm with hobnail microscopic morphology and unusual gross features

Vascular tumors are categorized into benign hemangiomas, frankly malignant angiosarcomas and tumors with intermediate biological behavior (hemangioendotheliomas). The latter group includes hemangioendotheliomas of the epithelioid, kaposiform, retiform and composite subtypes. Furthermore, a heterogeneous group of both benign and intermediate vascular tumors exhibits a peculiar hobnail cell morphology. This heterogeneous group encompasses hobnail hemangioma, retiform hemangioendothelioma, papillary intralymphatic angioendothelioma and a subset of angiosarcoma. We herein present a case of a cutaneous vascular neoplasm with hobnail morphology and unusual gross features.

Anastomosing hemangioma of the genitourinary tract: a lesion mimicking angiosarcoma

BACKGROUND

We describe 6 cases of a poorly recognized vascular neoplasm that can simulate angiosarcoma.

DESIGN

Cases of a rare vascular tumor with a proclivity for the genitourinary tract encountered in our consultation material were prospectively collected between the year 1999 and 2008. Follow-up information was obtained when possible.

RESULTS

There were 6 tumors from 4 men (66%) and 2 women, ranging in age from 49 to 75 years (median, 59.5) involving the kidney and renal hilum (4, 66%) and testis (2). Tumors ranged from 1.3 to 1.7 cm (median, 1.6 cm) and were grossly well-marginated with a hemorrhagic mahogany spongy appearance. Microscopically, at low power they had a loosely lobulated architecture and were associated with a medium-caliber vessel (5/6, 83%). Most kidney (3/4, 75%) tumors showed minor extensions into adjacent adipose tissue. At higher magnification, the tumors consisted of anastomosing sinusoidal capillary-sized vessels with scattered hobnail endothelial cells within a framework of nonendothelial supporting cells. There was a minimal inflammatory backdrop consisting of lymphocytes but not plasma cells or acute inflammation. Mitoses were absent (5/6, 83%) or rare (1 case; in supporting cells). There was mild cytologic atypia in one of the cases but no multilayering of endothelial cells in any case. Vascular thrombi were typical (5/6, 83%) and the lesions had zones of central sclerosis with focal necrosis (5/6, 83%). Two (33%) tumors featured prominent extra-medullary hematopoiesis and 2 tumors (33%) had striking hyaline globules reminiscent of those seen in Kaposi's sarcoma. Immunohistochemistry was available on some cases and the lesions stained with CD34, CD31, and FVIII but not human herpes virus type 8, keratin AE1/3, epithelial membrane antigen, HMB45, placental alkaline phosphatase, or human chorionic gonadotropin. In all but one submitted consultation, the possibility of angiosarcoma had been raised based on the anastomosing vascular pattern. On follow-up, there were no recurrences or metastases in 5 cases (range: 8 to 36 mo; median 12 mo, mean 15 mo), and 1 patient was lost to follow-up.

CONCLUSIONS

Anastomosing hemangioma of the genitourinary tract is a rare neoplasm displaying some overlapping features of both sinusoidal hemangioma and hobnail hemangioma of soft tissue and skin. However, in our opinion, it is a unique neoplasm with a proclivity for the kidney. Its anastomosing appearance can lead to concern for angiosarcoma but, despite small numbers and limited follow-up in our series, evidence to date supports that the lesion is benign.

Cutaneous vascular tumours: an update

This review evaluates changes in vascular nomenclature particularly in the category of vascular tumours of intermediate malignancy that includes the various haemangioendotheliomas, Kaposi's sarcoma and giant cell angioblastoma. Recently described entities in this category, including the latter tumour and composite haemangioendothelioma, are described. Several newly characterized vascular tumours not included in recent classifications of vascular tumours are also summarized. These include acquired elastotic haemangioma, symplastic haemangioma, cutaneous epithelioid angiomatous nodule and cutaneovisceral angiomatosis with thrombocytopenia. The newly introduced clinical classification of congenital haemangiomas into non-involuting and rapidly involuting variants and radiation-induced atypical vascular lesions are also reviewed.

Ileocecal hobnail hemangioendothelioma: report of a case and review of the literature

Hobnail hemangioendothelioma is a rare vascular neoplasm that belongs to the category of vascular neoplasms of borderline (or low-grade) malignancy, defined by a significant potential for local recurrence but very low numbers of metastatic or fatal events. It is typically found in the skin, and rarely in the oral mucosa of children and young adults. We report the first case of hobnail hemangioendothelioma located in the intestine (ileocecal valve).

Hobnail haemangioma associated with the menstrual cycle

We report the third case in the literature of a hobnail haemangioma with cyclic changes throughout the menstrual cycle in a 36-year-old woman, suggesting a hormonal basis for the variations in the tumour. This patient was under oral contraceptive treatment due to ovarian endometriosis, making the clinical diagnosis difficult.

Targetoid Hemosiderotic Nevus

BACKGROUND

Simulators of malignant melanoma comprise a heterogenous group of melanocytic and nonmelanocytic lesions of the skin. Among frequent clinical mimickers of melanoma are injured melanocytic nevi. Any change in the clinical appearance of a pre-existing nevus should alert the clinician to exclude the possibility of malignant transformation in order to early identify a lesion at a stage when complete cure can still be achieved.

OBJECTIVE

The purpose of this study was to present the clinical, dermoscopic and histopathologic findings of a series of acquired melanocytic nevi which abruptly developed a pigmented peripheral halo, presumably following minor trauma.

METHODS

A series of 6 cases of acquired melanocytic nevi which suddenly developed a targetoid halo were included in the study. All lesions were evaluated by dermoscopy. Three cases were surgically removed at different stages of evolution and submitted to histopathologic examination. In all cases, follow-up was obtained.

RESULTS

All the lesions arose on trauma-prone skin sites of young women. The sudden development of an asymptomatic, targetoid halo on a long-lasting, acquired exophytic nevus was the main presentation. Whereas the central nevus persisted, the ecchymotic halo ultimately disappeared. Histopathologic examination disclosed changes of the traumatized nevus in the central part, whereas the ring showed hemorrhage and hemosiderin deposits. Increased numbers of small vessels with hobnail characteristics were associated features.

CONCLUSIONS

Targetoid hemosiderotic nevus is a distinctive clinicopathologic variant of traumatized acquired melanocytic nevus which should be included in the list of clinical simulators of melanoma.

Lymphangioma-like Kaposi sarcoma

BACKGROUND

Lymphangioma-like Kaposi's sarcoma (LLKS) is a rare morphologic expression of Kaposi's sarcoma (KS) that occurs in virtually all of the well-recognized clinical subtypes of the disease and has the potential to mimic other pathologic processes. In this study, we present the clinical and pathological features of four patients with LLKS.

METHODS

Four cases of LLKS were retrieved from the dermatopathology files of our institution. All four tumours were tested immunohistochemically with anti-human herpesvirus-8 (HHV-8) latent nuclear antigen-1 (LNA-1) and anti-CD34 antibodies.

RESULTS

Clinically, each patient presented with violaceous patches, papules or plaques; one patient presented with bullous lesions. All of the LLKS biopsy specimens revealed areas with characteristic light microscopic features of KS. Lymphangioma-like foci consisted of ectatic, irregularly shaped vascular spaces lined by mildly atypical endothelial cells. All tumour cells, including those associated with LLKS foci, showed a strong and diffuse reactivity for anti-HHV-8 LNA-1 and anti-CD34. KS progressed slowly in two patients with adequate follow-up.

CONCLUSIONS

As LLKS can mimic other disease processes, the correct diagnosis relies heavily on the recognition of salient clinical and histological features of conventional KS, including a strong immunohistochemical expression of HHV-8-associated LNA-1 in lesional cells.

Vascular tumors of the skin: A selective review

Cutaneous vascular proliferations are a vast and complex spectrum. Many appear as hamartomas in infancy; others are acquired neoplasms. Some vascular proliferations are hyperplastic in nature, although they mimic hemangiomas, i.e., neoplasms. The vast majority of the vascular lesions are hemangiomas. Between the hemangiomas and frankly angiosarcomas, there is a group of neoplasms that are angiosarcomas, albeit ones of low grade histologically and, probably, biologically. The term "hemangioendothelioma" has been created to encompass these neoplasms. Vascular proliferations are, fundamentally, composed of endothelial cells. Some hemangiomas, however, contain also abundant pericytic, smooth muscle, or interstitial components, or a combination of them. These heterogeneous cellular components are present usually in hemangiomas. Some of the newly described vascular proliferations, however, are difficult to differentiate from some of the angiosarcomas. Others are markers, occasionally, of serious conditions such as Fabry's Disease (angiokeratoma) and POEM's syndrome (glomeruloid hemangioma). Kaposi's sarcoma continues to be an enigma. The demonstration of Herpes virus 8 in this condition raises doubt about its neoplastic nature. The demonstration of endothelial differentiation of its nodular lesions is tenuous and its true nature remains unresolved. While physicians have known about post-mastectomy angiosarcomas from the origin of the radical mastectomy, a new group of unusual vascular proliferations of the mammary skin are being defined. These lesions arise in the setting of breast-conserving surgical treatment with adjuvant radiation therapy. The incubation period is usually 3 to 5 years, in contrast with the 10, or more, in classical cases of post-mastectomy angiosarcoma. These lesions usually are subtle, both clinically and histologically, in contrast with the "classical," dramatic presentation of mammary angiosarcoma. The spectrum of findings ranges from "simple" lymphangiectasia-like vascular proliferations to unequivocal angiosarcomas. The pathogenesis of these lesions remains a mystery. There are very few clues that allow one to separate hemangiomas from angiosarcomas. The presence of heterologous cellular elements and, particularly, well-developed smooth muscle components tends to favor a hemangioma. Similarly, the presence of thrombosis usually supports hemangioma. Nevertheless, there are no unequivocal or reliable individual diagnostic criteria. A thorough knowledge of the different conditions and their differential diagnoses eventually leads to the proper diagnosis in most cases.

Hobnail hemangiomas (targetoid hemosiderotic hemangiomas) are true lymphangiomas

BACKGROUND

Hobnail hemangioma (targetoid hemosiderotic hemangioma) is a small benign vascular tumor of the superficial and mid-dermis. In contrast to its well-characterized histology, it has been unclear whether this tumor arises from blood vessel endothelial cells (BECs) or lymphatic vessel endothelial cells (LECs).

METHODS

We analyzed 10 hobnail hemangiomas by immunohistochemistry, using the recently described lymphatic endothelial cell marker, D2-40. For comparison, CD31, CD34, and alpha-smooth muscle actin expression were studied in consecutive sections of the paraffin-embedded tissues.

RESULTS

In all analyzed vessels, D2-40 labeled exclusively LECs, whereas BECs were consistently negative. In contrast to capillary BECs, either neighboring the tumors or intermingled, neoplastic endothelial cells of all 10 hobnail hemangiomas were strongly labeled by D2-40.

CONCLUSIONS

The results suggest a lymphatic origin for hobnail hemangiomas. This view is further supported by the CD34 negativity of endothelial cells and the lack of actin-labeled pericytes in hobnail hemangiomas, both characteristic of lymphatic vessels. Moreover, our analysis revealed that microshunts between neoplastic lymphatic vascular channels and small blood vessels occur, explaining some features of hobnail hemangiomas, such as aneurysmatic microstructures, erythrocytes within and beneath neoplastic vascular spaces, inflammatory changes, scarring, and interstitial hemosiderin deposits.

Endothelial lesions of soft tissues: a review of reactive and neoplastic entities with emphasis on low-grade malignant ("borderline") vascular tumors

Soft tissue proliferations composed of endothelial cells are a heterogeneous group of lesions that can cause diagnostic difficulty. Further complicating the issue is the constantly changing nomenclature of some entities, as well as reclassification of some vascular tumors from the high-grade malignant category to the low-grade malignant or borderline category. Modern ancillary techniques such as immunohistochemistry and cytogenetics have done little to advance our knowledge of these lesions. This review article outlines the most recent classification of endothelial lesions of the skin and soft tissues, with emphasis on the low-grade malignant (borderline) category. In addition, many tumor-like lesions containing an endothelial component are also discussed.

Acquired elastotic hemangioma: A clinicopathologic variant of hemangioma

BACKGROUND

In recent years, many new cutaneous vascular proliferations have been described. This is partly due to the current epidemic of AIDS, which has forced dermatopathologists to establish the diagnosis of the earliest patch-stage lesions of AIDS-related Kaposi's sarcoma and some of the recently described cutaneous vascular proliferations that may histopathologically mimic lesions of early Kaposi's sarcoma.

OBJECTIVE

This article reports the clinical, histopathologic, and immunohistochemical findings in 6 cases of a clinicopathologic variant of cutaneous hemangioma, which we have named acquired elastotic hemangioma.

METHODS

Six cases of acquired elastotic hemangioma were studied from clinical, histopathologic, and immunohistochemical standpoints. The histopathologic differential diagnosis with other similar cutaneous vascular proliferations is discussed.

RESULTS

Acquired elastotic hemangioma appears on the sun-damaged skin of the dorsal aspect of the forearms or on the lateral aspects of the neck of middle-aged or elderly women. Clinically, lesions present as solitary erythematous plaques with variable morphology and in only some cases have a clearly angiomatous appearance. On histopathologic examination, acquired elastotic hemangioma is characterized by a band-like proliferation of capillary blood vessels involving the superficial dermis and arranged horizontally parallel to the epidermis.

CONCLUSION

Acquired elastotic hemangioma is a distinctive clinicopathologic variant of hemangioma that should be differentiated from other cutaneous vascular proliferations. On histopathologic examination, it is characterized by capillary proliferation involving the dermis.

Absence of HHV-8 DNA in hobnail hemangiomas

BACKGROUND

Hobnail hemangioma (HH) is a rare subtype of hemangioma that shares the morphological feature of hobnail endothelia with retiform hemangioendothelioma (RHE) and has to be considered in the differential diagnosis of Kaposi sarcoma. Since DNA of the human herpesvirus type 8 (HHV-8) has been detected in more than 90% of Karposi sarcomas and could recently be demonstrated in RHE, we sought to detect HHV-8 DNA in HH.

METHODS AND RESULTS

DNA from 12 HH was extracted and subjected to polymerase chain reaction analysis for HHV-8 DNA using two independent protocols with a single set of primers and a nested PCR approach, respectively. PCR amplification was performed using the LightCycler as well as using a thermocycler. HHV-8 DNA could not be detected in HH, although each sample contained DNA adaequately preserved for PCR reactions, as determined by amplification of the beta actin gene.

CONCLUSIONS

HHV-8 appears to play no rule in the pathogenesis of HH. Absence of HHV-8 DNA in HH might be important in the differential diagnosis to other vascular tumours, in particular Kaposi sarcoma.

Trauma-induced simulator of targetoid hemosiderotic hemangioma

Reported here is a 15-year-old with lesions demonstrating histologic features of targetoid hemosiderotic hemangioma (THH) developing after trauma to inflammatory lesions. These lesions pose as simulators of THH. Targetoid hemosiderotic hemangioma is a benign vascular lesion first described by Santa Cruz and Aaronburg. It classically presents as a single, small, red/brown, targetoid lesion on the trunk or extremities of a young or middle-aged individual. Histologically, it is characterized by ectatic vascular lumina in the papillary dermis lined by a single layer of endothelial cells with an epithelioid or "hobnail" appearance. In the deeper dermis, vascular spaces become slit-like and angulated, appearing to dissect through collagen bundles. A commonly proposed etiology of THH is trauma to a preexisting hemangioma. This case is remarkable for its unusual clinical presentation, histologic simulation of THH, and for its support for the theory that trauma can induce the histologic changes seen in THH.

Benign lymphangioendothelioma (acquired progressive lymphangioma): a lesion not to be confused with well-differentiated angiosarcoma and patch stage Kaposi's sarcoma: clinicopathologic analysis of a series

The clinicopathologic features of 12 cases of benign lymphangioendothelioma (acquired progressive lymphangioma) are reported. There were five male and seven female patients. Age at diagnosis ranged from 17 to 90 years (median age, 54 yrs). Development of a single macular/papular hemangiomatous or pigmented lesion was the main presenting symptom. Symptom duration before diagnosis ranged from 2 months to 20 years (median, 5.5 yrs). Tumor size ranged from 0.3 cm to 10 cm (median. 1.5 cm). Location included skin of the head and neck (n = 5), back (n = 1), breast (n = 1), shoulder (n = 1), forearm (n = 1), plantar aspect of the foot (n = 2), and oral mucosa (n = 1). No patient had any other concomitant vascular anomaly (for example, lymphangiomatosis) or was suspected to have acquired immunodeficiency syndrome. Treatment consisted of excisional biopsy in nine patients, incisional biopsy in two, and wide excision in one. Follow-up information on nine patients (range, 4-40 mos; median, 12 mos) showed two local recurrences in one patient. Microscopically, the lesions consisted of anastomosing, often widely dilated vascular structures developing in the superficial dermis. As the lesion grew within deeper dermis, the vascular spaces collapsed and dissected the dermal collagen in an angiosarcoma-like pattern. The lining endothelium was flat and monolayered, with little or no cytologic atypia and no evident mitoses. Some vascular structures contained stromal papillary projections resembling papillary endothelial hyperplasia, and intravascular red blood cells were present occasionally. Immunohistochemistry performed in eight specimens showed variable endothelial cell reactivity for CD31 (7 of 8), CD34 (7 of 7), and factor VIII-related antigen (4 of 6). A smooth muscle cell layer was observed focally around the vascular spaces in six lesions. Benign lymphangioendothelioma (acquired progressive lymphangioma) is an uncommon benign lesion that, in view of major differences in treatment and prognosis, should be distinguished from well-differentiated angiosarcoma and Kaposi's sarcoma, especially the patch stage and lymphangioma-like variants of the latter.

Biological continuum of benign, atypical, and malignant mesenchymal neoplasms - does it exist?

The characterization of specific cytogenetic and molecular abnormalities in benign and malignant soft tissue tumours has increased our understanding and knowledge of the biology of these rare neoplasms in recent years and has led to the modification of a number of traditional classification schemes. Contrary to popular belief, it is reasonable to propose that there exists a molecular, genetic, and morphological continuum of benign, atypical, and malignant mesenchymal neoplasms. The identification of characteristic molecular changes in benign lipomas, lipomas with minimal atypia, and atypical lipomatous tumours, well-differentiated liposarcomas supports the hypothesis of a stepwise process in the pathogenesis of these neoplasms. Not only are these findings important for our understanding of the biology of soft tissue tumours, but they also may increase diagnostic and prognostic accuracy.

Benign lymphangiomatous papules of the skin following radiotherapy: a report of five new cases and review of the literature

AIMS

The aim of this report is to summarize the clinicopathological findings of five cases of a pseudosarcomatous vascular proliferation of the skin at the site of radiotherapy following surgery for carcinoma of the breast and carcinoma of the endometrium. To our knowledge, only five cases of this presumably rare pseudomalignant proliferation have been reported previously.

METHODS AND RESULTS

All patients were females ranging in age from 44 to 70 years. The lesions appeared as solitary or multiple papules or vesicles localized to the field of radiation. Microscopically, they were composed of vascular spaces that exhibited atypical features without qualifying for a diagnosis of angiosarcoma.

CONCLUSIONS

Our cases provide additional evidence supporting the benign nature of this atypical vascular proliferation, not recurring, never developing metastases and being cured readily by local excision. Clinical, histopathological and ultrastructural findings suggest a lymphatic origin. Whether these lesions represent a neoplastic or a reactive condition secondary to radiotherapy is unclear. The name 'benign lymphangiomatous papules of the skin following radiotherapy' is proposed.

Hobnail hemangioma ("targetoid hemosiderotic hemangioma"): clinicopathologic and immunohistochemical analysis of 62 cases

Hobnail hemangioma, also known as "targetoid hemosiderotic hemangioma", represents a distinctive, benign vascular tumor, characterized histologically by a biphasic growth pattern of dilated vascular structures in the superficial dermis lined by prominent hobnail endothelial cells, and collagen dissecting, rather narrow neoplastic vessels in deeper parts of the lesion. We analyzed the clinicopathologic and immunohistochemical features in a series of 62 cases. Patient age range was 6-72 years (median: 32 years); 34 patients were male and 25 female. Clinically, a broad variation of diagnoses ranging from hemangioma to dermal melanocytic nevus and fibrous histiocytoma was suggested. Nineteen tumors arose in the lower and 13 in the upper extremities, 12 on the back, 8 in the buttock and hip region, and one case on the chest wall. Follow-up information on 35 patients (range from 1 to 4 years; mean: 1.5 years) revealed no local recurrence nor systemic metastasis. All neoplasms were located in the dermis and showed a broad morphologic spectrum in dependence of the age of the lesions. In addition to lesions resembling cavernous lymphangioma or lymphangioma circumscriptum, neoplasms were seen with morphologic features reminiscent to retiform hemangioendothelioma, progressive lymphangioma and so-called Dabska's tumor. Immunohistochemistry performed in 28 cases showed positive staining of tumor cells for CD31 in all cases tested, whereas only 3 out of 28 cases stained completely positive for CD34. In addition 4 out of 8 cases stained positively for vascular endothelial growth factor receptor-3 (VEGFR-3). Neoplastic endothelial cells were surrounded by actin-positive pericytes in only 7 out of 27 cases tested. Hobnail hemangioma occurs more frequently in male patients and arises commonly in the extremities and the trunk. Histologic and immunohistochemcial features suggest a lymphatic line of differentiation for this distinctive vascular neoplasm.