Pilomatrixoma

At a glance

A benign skin appendage tumor frequently involving the skin of the head, neck, and upper extremities in young children.

Synonyms

Epithelioma Calcificans of Malherbe; Pilomatricoma Malherbe Epithelioma; Malherbe Tumor; Calcifying Epithelioma of Malherbe; Malherbe Calcified Epithelioma.

Incidence

Isolated lesions are not rare in children with antecedent trauma, which has been described in 30% of cases. Pilomatrical neoplasms are considered the most common solid cutaneous tumors in patients 20 years of age or younger. In the United Kingdom, pilomatrixomas account for 1 in 500 histologic specimens. The female-to-male ratio is 1.5:1.

Genetic inheritance

Isolated lesions are sporadic. The presence of multiple lesions may be suggestive of an autosomal dominant transmission. In this case, it may be associated with ☞Myotonic Dystrophy, ☞Sotos Syndrome, ☞Rubinstein-Taybi Syndrome, Gardner Syndrome or ☞Ullrich-Turner Syndrome.

Pathophysiology

The tumor arises from hair matrix cells. The cause has been suggested as the result of a mutation in the beta-catenin gene. Some cases of pilomatrixoma are caused by somatic mutation in the beta-catenin gene (CTNNB1) on chromosome 3p22.

Diagnosis

Pathologically, the tumors were situated in the dermis or subcutaneous tissue. The histopathologic findings of viable basaloid cells in the periphery, shadow cells in the central part, and foci of calcification are characteristic of pilomatrixoma. Computed tomography scans clearly demonstrated a well-defined, subcutaneous mass with amorphous calcifications. Lesions are most often discovered within the first 2 years of life.

Clinical aspects

This benign lesion is a firm, circumscribed tumor, 1 to 2 cm (0.4-0.8 inches) in diameter, usually in the head and neck area, attached to the subcutaneous tissue and overlying skin. Usually it is an asymptomatic superficial mass that increased slowly in size. Multiple lesions occur in 2 to 3% of reported series, in some cases in association with myotonic dystrophy. Complete surgical excision is the best management.

Precautions before anesthesia

Presence of other syndromes should be sought in any patient with more than one pilomatrixoma and in any patient with a family history of pilomatrixoma.

Anesthetic considerations

Isolated pilomatrixoma do not represent an anesthetic problem. However, the presence of ☞Myotonic Dystrophy, ☞Sotos Syndrome, ☞Rubinstein-Taybi Syndrome or ☞Ullrich-Turner Syndrome dictates the choice and conduct of the anesthesia.

Pharmacological implications

Isolated pilomatrixoma does not have any special pharmacological implications. The use of neuromuscular blocking agents should be used with cautions.

References