Are You Confident of the Diagnosis?
What you should be alert for in the history
Also known as targetoid hemosiderotic hemangioma, the diagnosis of hobnail hemangioma (HH) is often made in the setting of an acquired, small, annular, violaceous or brown papule surrounded by an ecchymotic ring. This is a rare, benign vascular neoplasm that usually presents on the extremities or trunk of a young to middle-aged adult. The duration of the lesion is variable and has been reported to occur in individuals ranging from ages 5 to 72. HH is soft on palpation and usually asymptomatic, although it may be intermittently painful, especially when located in an area where it may have been traumatized.
Characteristic findings on physical examination
Classically, the small papule is surrounded by a thin pale area and a peripheral ecchymotic ring, resulting in a targetoid appearance (Figure 1). In later stages, the halo and ring surrounding the papule often disappear and resolve. However, these patients can often remember an ecchymotic or “bruised” appearance surrounding the papule on questioning. Recent studies have shown that only a minority of lesions exhibits this classic halo, and instead, the clinical appearance is actually widely variable.
The papule is solitary and usually measures approximately 2 to 3mm in diameter, but has been described as up to 2cm in size. The presenting lesion can alternatively be pigmented or flat. Flat lesions are more likely to be asymptomatic. The color can also be variable, and a few lesions exhibit a black, gray, or tan appearance. Regression and fluctuation of color, size, and/or morphology can also be apparent. Patients may present after noticing changes or fluctuations in the lesion, but usually present with cosmetic concerns or to rule out malignant processes.
Common locations include the lower limb, particularly the thigh, the arm, especially the shoulder area, the back, buttock, hip, and chest. Uncommonly, hobnail hemangiomas have also been described on the face, gingiva, and the tongue.
Expected results of diagnostic studies
Because of the variability in clinical presentation, a confident diagnosis cannot usually be made based solely on clinical grounds. A skin biopsy is often necessary in order to confirm the diagnosis.
The diagnosis of hobnail hemangioma can be confirmed by its distinctive features on histopathology. The lesions display a biphasic growth pattern consisting of a superficial dermal component with widely dilated, thin-walled vascular lumina with intraluminal papillary projections, along with more narrow slit-like vessels that dissect between collagen bundles. The term hobnail comes from the single layer of prominent, plump endothelial cells that line the vessels.
These endothelial cells possess enlarged, somewhat hyperchromatic nuclei that bulge into the vascular lumina, resulting in the striking hobnail appearance. As they delve deeper into the reticular dermis, the vascular lumina become angulated and merge with deeper, smaller, slit-like vessels that grow and dissect between collagen bundles. The characteristically plump endothelial cells also become more flat in the deeper and narrower vascular structures. The vascular proliferation often extends into the subcutaneous tissue and can concentrate around adnexal structures.
Stromal hemosiderin deposits often appear in the later stages and can be extensive, but have also been noted to be absent in some cases of HH. The appearance of extravasated red blood cells is common. As the lesion matures, the vascular lumina can appear collapsed and the extravascular space becomes more cellular. It is important to get adequate tissue to at least the deeper portion of the dermis by excisional biopsy in order to assure that the other conditions in the differential diagnosis can be ruled out.
The use of immunohistochemical stains can also aid in the diagnosis. The characteristic endothelial cells are usually CD31 positive and only rarely CD34 positive. Dermal dendrocytes and periadnexal fibroblasts may stain CD34 positive. Immunoreactivity with vascular endothelial growth factor receptor-3 has been noted and may suggest the possibility of lymphatic derivation. The endothelial cells have also been noted to stain positive for Factor VIII antigen and to a lesser degree, Ulex europaeus-1 lectin. Neoplastic endothelial cells are commonly surrounded by actin positive perivascular pericytes.
Laboratory studies are usually not indicated but may be undertaken if the differential includes Kaposi’s sarcoma. In this case, immunoperoxidase study for HHV-8 on tissue can be performed or if there are risk factors for HIV an ELISA HIV antibody test could be considered.
Due to its wide variability in size, color, and morphology, the diagnosis of HH is often clinically uncertain. The differential diagnosis of hobnail hemangioma often includes similar appearing entities both benign and malignant in their courses, so that proper characterization of the lesion is important.
Clinically, hobnail hemangioma may resemble a melanocytic nevus, melanoma, insect bite reaction, or other benign hemangiomas. In these cases, the diagnosis may be readily distinguished by history or histopathology, if necessary. A history of fluctuating size, color, and morphology suggests hobnail hemangioma, whereas melanocytic nevi and melanomas may change in size, color, or morphology but do not characteristically demonstrate waxing and waning. Melanocytic nevi and melanomas also possess structural patterns and pigment networks not seen in HH.
The presence of constitutional symptoms and the proper history can implicate an insect bite, and Warthin-Starry or Dieterle staining methods can be used to investigate for spirochetes if appropriate. The age of the patient and histopathology characterizes hemangioma from the hobnail form, as hemangiomas are usually apparent from birth and lack the biphasic growth pattern characterize of hobnail hemangioma.
Atypical vascular lesions of the skin occurring after radiation therapy can be clinically similar as well. Clinical correlation is often adequate in distinguishing these lesions from HH, but if necessary, the diagnosis can be ruled out histopathologically by its lack of the distinctive hobnail endothelial cells, dissection of dermal collagen by angulated vessels, and hemosiderin deposition. The clinical appearance of hobnail hemangioma in its classic targetoid form may resemble halo nevus or primary amyloidosis, with histopathology often required to distinguish between these conditions.
Kaposi’s sarcoma (KS) is a worrisome condition often seen in the context of HIV and HHV-8 infection that may enter the differential based on similar clinical and histologic characteristics, especially in its patch stage. However, defining histopathologic characteristics of KS include the presence of clusters of plasma cells and apoptotic endothelial cells not seen in HH. KS also does not display the widely dilated vascular spaces in the superficial dermis or the plump hobnail appearance of endothelial cells of HH. The endothelial cells of KS exhibit HHV-8 DNA. Clinically, KS differs from HH in that it usually appears either as widespread, multiple lesions in the setting of an immunocompromised patient or as lower extremity lesions in immunocompetent elderly patients of Jewish or Mediterranean descent.
Cutaneous angiosarcomas may also enter the differential diagnosis, but these are usually multiple blue nodules or macules occurring on the face, neck, and scalp of elderly adults that exhibit atypia with spindle cell and/or epithelioid components under the microscope. The newly characterized lesion retiform hemangioendothelioma is another similar low grade angiosarcoma that may represent the malignant form of HH. In these patients, recurrences are common, and a marked lymphocytic infiltrate usually accompanies arborizing dermal blood vessels that appear similar to the architecture of rete testis on histopathology. Retiform hemangioendothelioma is also characterized by an infiltrative growth pattern, which is not characteristic of HH.
Dabska’s tumor is a low-grade angiosarcoma with metastatic potential usually in the skin or subcutaneous tissue of infants or young children. In contrast to Dabska’s tumor, HH is more superficially located and circumscribed and lacks infiltrative growth. Histopathologically, Dabska’s tumor exhibits unique, complex, multilayered endothelial tufting. Benign lymphangioendothelioma can appear clinically as a bruise-like macule or plaque but is usually large (greater than 10cm) and lacks the hobnail endothelial cells and hemosiderin deposits of HH.
Who is at Risk for Developing this Disease?
The prevalence of hobnail hemangioma is unknown. Recent studies have indicated that there is an equal male to female distribution. There is no known racial association, although the presence of this vascular lesion has only been described in Caucasians.
What is the Cause of the Disease?
The etiology of HH is unknown, but many theories have been proposed to explain the cause of these lesions. Trauma may be a predisposing factor. One commonly proposed mechanism is that HH results from trauma to a preexisting hemangioma, but many reports indicate that a preexisting lesion is not necessary for HH to arise. One report suggests that belt irritation can be an inciting agent of HH. Some believe that HH is a larger, more traumatized variant of solitary angiokeratoma. The fluctuation and changes in the size, color, morphology, and peripheral halo may also be caused by recurring trauma or vessel fragility.
Another theory proposes that this waxing and waning nature is related to hormonal changes associated with pregnancy and the menstrual cycle. This hypothesis suggests that fluctuating estrogen levels may lead to vascular instability and the red blood cell extravasation seen in HH. However, it is important to note that no hormone receptors have been detected in HH.
Systemic Implications and Complications
Recognizing and correctly diagnosing hobnail hemangioma is important in order to distinguish this benign lesion from other similar-appearing and potentially malignant processes. Hobnail hemangioma is a localized lesion that itself has no malignant or metastatic potential and follows a benign course. There are no systemic complications.
Treatment options are primarily surgical. Complete excision of the lesion is recommended for diagnostic purposes and results in resolution of the entire lesion, including the ecchymotic ring if present. There is no local recurrence after surgical excision. Spontaneous resolution of the lesion has also been described, and local recurrence is possible in these cases.
Optimal Therapeutic Approach for this Disease
A comprehensive history and physical examination must first be performed. Be sure to perform a complete skin examination to observe for the presence of similar lesions. Inquire about HIV risk factors and the possibility of immunosuppression, especially if multiple lesions are present. Inquire about the possibility of a previous insect bite at the area, a personal or family history of melanoma, and the presence of constitutional symptoms. Ask if the patient has noticed any changes to the lesion, or if the lesion has been present in the past and spontaneously resolved.
Educate patients regarding the benign nature and course of this condition. Discuss the benefits and risks to performing an excisional biopsy for management and to confirm the diagnosis versus observation without intervention.
The recommended approach is to perform an excisional biopsy and send for pathology to confirm the diagnosis, rule out malignant neoplasms, and prevent possible recurrence. For patients in whom the hobnail hemangioma has resolved spontaneously, counsel the patients to observe for recurrence or change to the area. Lesions can be surgically excised if they recur.
Because this is a benign lesion with no potential for metastasis and no evidence of recurrence after surgical excision, no long-term follow-up is required after excision of hobnail hemangioma. Adequate routine follow-up is necessary after excisional biopsy to remove stitches and ensure proper healing and the absence of infection. In the case of spontaneous resolution of a hobnail hemangioma, patients should be counseled to observe for local recurrence. The lesion can then be removed for cosmetic and diagnostic purposes or if symptomatic.
Unusual Clinical Scenarios to Consider in Patient Management
Because the clinical appearance of HH is so variable, unusual presentations may occur. The class targetoid appearance may be absent. The color can vary from tan-brown, to red-purple, black, or gray, and may fluctuate between these colors. The size of the lesion can intermittently change as well, or even completely regress. It is important to carefully consider all features of the patient’s presentation to assess for other etiologies.
What is the Evidence?
Santa Cruz, DJ, Aronberg, J. “Targetoid hemosiderotic hemangioma”. J Am Acad Dermatol. vol. 19. Sept 1988. pp. 550-8. (The original piece of literature describing targetoid hemosiderotic hemangioma, this paper first characterized the lesion and discussed both histopathologic and clinical steps to the diagnosis.)
Guilloi, L, Calonje, E, Speight, P. “Hobnail hemangioma: a pseudomalignant vascular lesion with a reappraisal of targetoid hemosiderotic hemangioma”. Am J Surg Pathol. vol. 23. 1999. pp. 97-105. (A study of 15 patients that closely examined the histopathologic characteristics of targetoid hemosiderotic hemangioma and etiologies in the differential diagnosis. The authors suggested a change from the clinical term “targetoid hemosiderotic hemangioma” to “hobnail hemangioma” to better account for the distinctive histopathological characteristics and to encompass lesions that appear similar on pathology but lack the targetoid clinical appearance or vary in their degree of hemosiderin deposition.)
Mentzel, T, Partanen, TA, Kutzner, H. “Hobnail hemangioma (“targetoid hemosiderotic hemangioma”): clinicopathologic and immunohistochemical analysis of 62 cases”. J Cutan Pathol. vol. 26. 1999. pp. 279-86. (This excellent review of 62 cases details the distinctive histopathologic, and immunohistochemical qualities of HH, distinguishing this entity from other similar conditions that may enter the differential diagnosis.)
Morganroth, GS, Tigelaar, RE, Longley , BJ, Luck, LE, Leffell, DJ. “Targetoid hemangioma associated with pregnancy and the menstrual cycle”. J Am Acad Dermatol. vol. 32. 1995. pp. 282-4. (This report of HH in a 38-year-old woman suggested that hormonal changes associated with pregnancy and menstrual flow affects its pathogenesis and fluctuating morphology.)
Tan, C, Zhu, WY, Lai, RS. “A recurrent case of targetoid hemosiderotic haemangioma”. Acta Derm Venereol. vol. 88. 2008. pp. 181-2. (HH may locally occur after spontaneous resolution, as evidenced in this report of a 9-year-old boy. This is an important consideration in counseling patients and maintaining follow-up for HH.)
Ghibaudo, N, Lacour, JP, Argenziano, G, Ortonne, JP, Bahadoran, P. “Fully regressive targetoid haemosiderotic haemangioma”. J Eur Acad Dermatol Venereol. vol. 23. Jun 2009. pp. 722-3. (This report of THH in a 48-year-old woman showed full regression of the ecchymotic ring within 1 month and the entire lesion within 3 months, without scarring.)
Rapini, RP, Golitz, LE. “Targetoid hemosiderotic hemangioma”. J Cutan Pathol. vol. 17. 1990. pp. 233-5. (This early report of targetoid hemosiderotic hemangioma supplemented Santa Cruz and Aronberg’s discussion of the lesion. This report also described THH developing in the area of the beltline, proposing the notion that trauma may play a role in its etiology.)
Gutzmer, R, Kaspari, M, Herbst, RA, Kapp, A, Kiehl, P. “Absence of HHV-8 DNA in hobnail hemangiomas”. J Cutan Pathol. vol. 29. 2002. pp. 154-8. (The detection of HHV-8 DNA is an important indicator of Kaposi’s sarcoma and has more recently been demonstrated in retiform hemangioendothelioma, two conditions that may mimic hobnail hemangioma. By demonstrating the lack of HHV-8 DNA in hobnail hemangiomas, an important diagnostic distinction was made that can aid in future diagnoses.)
Christenson, LJ, Stone, MS. “Trauma-Induced simulator of targetoid hemosiderotic hemangioma”. Am J Dermatopathol. vol. 23. 2001. pp. 221-3. (This report of two hobnail hemagiomas arising on a 15-year-old patient suggests that trauma (excoriation and manipulation) was the main predisposing factor. This report also proposed that a preexisting lesion is not necessary for a hobnail hemangioma to arise.)
Carlson, JA, Daulat, S, Goodheart, HP. “Targetoid hemosiderotic hemagioma- a dynamic vascular tumor: report of 3 cases with episodic and cyclic changes and comparison with solitary angiokeratomas”. J Am Acad Dermatol. vol. 41. Aug 1999. pp. 215-24. (Solitary angiokeratomas can appear similar to targetoid hemosiderotic hemangiomas in both clinical appearance and histopathology. This report suggests that targetoid hemosiderotic hemangiomas are actually a more extensive and larger variant of solitary angiokeratoma. A comprehensive comparison of the two vascular entities reveals many striking similarities. The article also favors the notion that trauma is an important predisposing factor in the development of targetoid hemosiderotic hemangiomas.)
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