Scalp actinomycosis presenting as soft tissue tumour: A case report with literature review

Actinomycosis is a rare subacute or chronic bacterial infection caused by Gram positive, anaerobic or microaerophilic bacilli. It is characterized by suppuration, abscess formation, tissue fibrosis, draining sinuses & rarely as a soft tissue mass mimicking a tumor.

A 16 year old boy sustained a trauma over right forehead & wound after which patient presented with swelling over right forehead which was excised and was histopathologically reported as angiomatous lesion. Patient presented with recurrent swelling with ulceration over the same site. CT scan showed soft tissue mass with periosteal reaction of right frontal bone. Wide local excision with removal of periosteum was carried out. Raw area was covered with rotational scalp flap. Histopathology of the excised specimen showed features of actinomycosis.

Cutaneous actinomycosis presenting as pseudocarcinomatous or sarcomatous mass is rare. Trauma is a common preceding event which was observed in present case. Histopathological confirmation is mandatory with visualization of sulfur granules. It is managed by high dose IV antibiotics. Surgical resection is a useful adjuvant therapy specially in large, disfiguring masses not responding to medical treatment and where excisional biopsy is helpful in establishing the diagnosis surgical excision alone is not curative, post operative long term antibiotics are adjuvant therapy to avoid recurrence.

Actinomycosis of scalp skin is a rare entity and tumor like presentation is still uncommon. Lesions not resolving with routine antibiotics therapy should be suspected clinically as actinomycosis and treated with high dose antibiotics as histopathology from small biopsy is unreliable.