Superficial angiomyxoma - Clinicopathologic analysis of a series of distinctive but poorly recognized cutaneous tumors with tendency for recurrence

Despite being first described in 1988, superficial angiomyxoma is still a p oorly recognized cutaneous tumor. Although its histologic features are dist inctive, its existence seems not to be widely accepted. We analyzed the cli nicopathologic and immunohistochemical features in a series of 39 cases. Tw enty-five patients were males; age range was birth to 82 years (median, 45. 5 years). Most cases presented as cutaneous papules, nodules, or polypoid l esions. Seventeen tumors arose on the trunk, 14 on the head and neck, and s even on the lower limbs. All cases were treated by local excision, and eigh t recurred locally. In four of the latter cases, there were two recurrences . Histologically, the lesions were dermal with variable involvement of the subcutis. Tumors were poorly circumscribed, but a focal lobular outline was always identified. Distinctive histologic features included extensive myxo id stroma, numerous small blood vessels, varying cellularity, acellular muc in pools, stellate or bipolar fibroblastic cells, muciphages, a sparse, mix ed inflammatory cell infiltrate with notable neutrophils, and occasional pl umper cells with eosinophilic cytoplasm. Cytologic atypia was mild at most, and mitotic figures were rare. In approximately 20% of casts, the primary lesion or its recurrence contained epithelial structures, including epiderm oid cysts, thin strands of squamous epithelium, and small buds of basaloid cells. Immunohistochemically, tumor cells were negative for S-100 protein, smooth muscle actin, and pan-keratin. We support the concept of superficial angiomyxoma as a distinctive clinicopathologic entity that should be inclu ded in the differential diagnosis of other myxoid cutaneous tumors, includi ng dermal nerve sheath myxoma, trichodiscoma and trichofolliculoma, and low -grade myxofibrosarcoma.