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Alveolar soft-part sarcomas are clinically and morphologically distinct soft-tissue sarcomas, with an unknown histogenesis. When the tumors affect the region of the head and neck, they are often located in the orbit and tongue. We report a case of an alveolar soft-part sarcoma in the left masseter of a 28-year-old female. The patient had chronic pain and paresthesia of her left lower lip. Panoramic radiography and computed tomography showed a well-delimited radiolucent mass in the left ramus. An incisional biopsy was performed, and the sample submitted for histopathological study. The tumor showed positive periodic acid-Schiff diastase-resistant granules. Immunohistochemically, the tumor cells were diffusely positive for myoglobin, and focally positive for actin and desmin.

In Chile, loxoscelism is caused by the bite of the Loxosceles laeta spider. The clinical presentation has two different forms: cutaneous loxoscelism (CL) and vicero-cutaneous loxoscelism, which is less frequent. Cutaneous loxoscelism includes an uncommon clinical variation (4%), called CL with edematous predominance (CLEP). We present a 5-year-old patient with sudden pain and edema on his right eyelid associated with fever, which progressed rapidly involving the right hemifacial area, frontal region, and left eyelid. Angioedema and pre-orbital cellulitis were discarded and CLEP was suspect. Cutaneous loxoscelism with an edematous predominance is self-limited, benign and with little or no necrotic injury due to the edema, which dilutes the toxin-induced enzymatic process causing necrosis. As in the reported cases it usually responds well to medical treatment and does not cause visceral involvement.