Histiocytoid Hemangioma - An Insight

What Is Histiocytoid Hemangioma?

Histiocytoid hemangioma is a group of rare tumors of small blood vessels; these tumors are considered to be developed due to the proliferation of epitheloid endothelial cells. These lesions are commonly found on or beneath the skin surface. These benign tumors are also known as angiolymphoid hyperplasia with eosinophilia and were first described by Rosai et al. in 1979. The most common site for histiocytoid hemangioma is the skin of the scalp, but it can also involve other sites. These tumors are considered to be caused by a mutation in the MALT1 gene (Metastasis Associated Lung Adenocarcinoma Transcript 1).

Which Tumors Are Included in the Group of Histiocytoid Hemangioma?

A histiocytoid hemangioma is a group of disorders that have characteristic histologic findings and the tumors consist of histiocytoid endothelial cells. Below mentioned are the lesions included in the category of histiocytoid hemangioma:

• Atypical Pyogenic Granuloma: It is a common benign mucocutaneous lesion that is commonly associated with local irritation or trauma).

• Pseudopyogenic Granuloma: These are inflammatory angiomatous nodules with abnormal blood vessels that occur around the ears and scalp).

• Angiolymphoid Hyperplasia With Eosinophilia: It is also known as epithelioid hemangioma, which is a benign vasoproliferative disorder. The pathogenesis of this disease is not yet understood clearly. It usually shows papules or nodules usually involving the head and neck region.

• Kimura's Disease: It is also known as Eosinophilic Granuloma: It is a rare chronic disorder that mainly occurs in the Oriental population. It shows lymphadenopathy, subcutaneous nodules, and salivary gland hypertrophy with peripheral eosinophilia, along with raised serum immunoglobulin E levels. Renal involvement may also be seen in rare cases.

• Inflammatory Arteriovenous Hemangioma: A hemangioma is a benign or noncancerous tumor composed of blood vessels. There are various types of hemangiomas, and they can be seen throughout the body.

All the conditions mentioned above have similar and characteristic histological findings.

What Is the Etiology of Histiocytoid Hemangioma?

The tumor is considered to be of unknown origin, but various studies suggest the role of different etiologic factors that initiate and cause the tumors. Some of the commonly known etiological factors include epithelial cells in tumor formation. The proliferation of endothelial cells characterizes these lesions; thus, it is considered these cells play an important role in the formation of histiocytoid hemangioma. Gene mutation also plays a role in the development of the lesion. And research reveals the role of genetic mutation in the onset of the tumor the gene responsible is considered the MALT1 gene.

What Are the Common Sites of Histiocytoid Hemangioma?

Histiocytoid hemangioma is a rare benign tumor. As they have an epitheloid origin, they are commonly found on the surfaces of the skin or beneath the skin. Some of the common sites for these tumors are:

• The scalp or the skin of the head.

• Oral mucous membrane.

• Nails.

• Testis.

• Bones.

• Colon.

• Epididymis.

What Are the Symptoms of Histiocytoid Hemangioma?

The patient does not present with any significant clinical symptoms; some of the symptoms that can be observed are as follows:

• The affected site appears pink or red.

• Itching.

• Swelling or bumps are usually near the affected vessels.

• Tenderness.

• Pain (it rarely occurs on compression of the adjacent vessels).

How Is Histiocytoid Hemangioma Diagnosed?

Diagnosis of histiocytoid hemangioma is difficult. Therefore, any single diagnostic method cannot conclude the diagnosis; the following are the diagnostic methods used:

Clinical Examination:

On clinical examination, tender swelling on the skin surface is observed the region is discolored with red or pink color on the surface. The site is usually adjacent to the vessels. These lesions might cause slight or no pain and, therefore, can go unnoticed.

Histological Examination:

When stained with hematoxylin and eosin (H&E )stain and studied under a microscope, the section of the lesion shows.

• The proliferation of small blood vessels.

• Proliferated capillary-sized blood vessels are lined by epitheloid endothelial cells.

• Cytoplasm shows a tombstone appearance (cytoplasm spikes into the lumen).

• Many eosinophils, lymphocytes, mast cells, and plasma cells are observed in the stroma, suggesting chronic inflammation.

• A single, large nucleus with fine chromatin and central nucleolus is present.

Even though microscopic examination reveals so many histologic features, it does not help in concluding the diagnosis as similar histopathology is observed in other inflammatory, epithelial cell, and vascular disorders.

Imaging: Imaging techniques like MRI or CT scan are used to determine the extension of the lesion, vascular involvement, etc.

Immunohistochemistry: This laboratory test uses antibodies to check for antigens or cell markers like CD31 or CD34.

The diagnosis is confirmed by evaluating the findings of all the above-mentioned diagnostic tests. Early and accurate diagnosis is the key to a complete cure and good prognosis.

How Is Histiocytoid Hemangioma Treated?

Though the tumor is benign, it does not metastasize and is not even painful. It is important to treat the lesion and irradicate it completely to prevent further damage or compression of the adjacent blood vessels. Therefore following are the treatment modalities used to irradicate the tumor:

• Surgical Excision: This is considered the treatment of choice, as the mass is excised in toto (complete removal), which prevents the chances of recurrence and helps in quick recovery.

• Laser-Assisted Excision: This is the treatment of choice in cases with small, superficial lesions. It is a less invasive method, hence preferred.

• Pharmacotherapy: This is considered adjuvant therapy and helps prevent the lesion's progression and its recurrence. Medications like Pentoxifylline and Indomethacin farnesyl are the drugs of choice.

Chemotherapy, intralesional steroid injections, radiotherapy, and cryotherapy can also be used if and when required.

Conclusion:

Histiocytoid hemangioma is a rare benign tumor of small blood vessels commonly found on the skin's surface or beneath the skin; other regions commonly affected are the head, oral mucosa, bones, and nails. These tumors are commonly present adjacent to the small blood vessels and compress them to give the lesion a pink or red inflammatory appearance. These lesions are usually asymptomatic and painless, therefore, can be left undiagnosed. Histiocytoid hemangioma, when diagnosed, is treated surgically to prevent a recurrence. Therefore it can be concluded that histiocytoid hemangiomas are difficult to diagnose but treatable with a minimum recurrence rate.