Sinonasal seromucinous hamartomas (SSH) are benign sinonasal neoplasms.

Epidemiology

Sinonasal seromucinous hamartomas are rare, with approximately 25 cases reported since 1974 ¹. They are more common in middle-aged adults with a mean in the 6th decade and a slight female predilection (1.5:1) ^3,4. While these are usually seen in the adult population, they have been described in patients as young as 14 ².

Clinical presentation

Clinical presentation can vary, but most patients present with unilateral nasal obstruction ^3,4. However, some patients may also present with nasal discharge, choking sensation, epistaxis, or asymptomatic. Masses have ranged in size from 0.6 to 6.0 cm ⁵.

Pathology

Although imaging studies are helpful in the diagnosis, ultimately, histology is required. 

Microscopic appearance

Microscopically, these lesions are covered by ciliated respiratory or cuboidal epithelia with invaginations and variable glandular and cystic stroma ^2,3. Mitotic figures, cellular atypia, and necrosis are often absent ⁵. However, eosinophilic, or mucinous cells may be present ⁴.

Location

In most patients, cases have arisen from the posterior nasal cavity medial to the middle turbinate ⁵.

Radiographic features

MRI

MR (and CT to a lesser extent) are beneficial in determining localisation of disease. These lesions most commonly appear as lobulated masses in the posterior nasal cavity or nasopharynx with hyperintense T2 signal. They are not associated with invasion into adjacent tissue ^1,6.

Treatment and prognosis

These tumours are benign neoplasms. Surgery is often curative and there has only been one reported case of recurrence ².

Differential diagnosis

Differential diagnosis include:

• respiratory epithelial adenomatoid hamartoma

• low-grade sinonasal adenocarcinoma

• inflammatory polyp