Cutaneous bronchogenic cyst: an under-recognised clinicopathological entity
- Keloth E Pradeep, Wrexham Maelor Hospital, Wrexham, UK;
- Accepted 8 May 2008
A 25-year-old man presented with a tiny lesion on the suprasternal notch which occasionally discharged a clear fluid. The lesion was faint brown and measured 3 mm in maximum dimension and was not inflamed. Clinically, this was suspected to be a cyst.
Microscopic examination showed an unremarkable epidermis and the dermis contained a cystic space lined by bland pseudostratified respiratory type epithelium and adjacent seromucinous glands (fig 1).
Immunohistochemically, these structures were positive for thyroid transcription factor 1 (TTF-1) (fig 2). The appearances were those of a cutaneous bronchogenic cyst. Bronchogenic cyst is a benign congenital developmental abnormality of the embryonic foregut. Bronchogenic cysts are believed to form from buds or diverticula that separate from the foregut during development of the tracheobronchial tree. They may be intrapulmonary or peripheral.
Over 50 cases of cutaneous bronchogenic cyst have been reported in the English literature.1 Nevertheless, it is poorly recognised by clinicians and is sometimes confused with branchial cyst. In almost all cases the diagnosis is established by histopathological examination. This lesion is four times more common in men than in women and it has been reported in very young children.2 The most common location is the suprasternal notch, followed by the presternal area, neck and scapula. Occasionally they are seen on the skin of abdomen.3 The characteristic histological findings are a ciliated pseudostratified columnar lining with the presence of smooth muscle cells, seromucinous and goblet cells and, less frequently, cartilage. Some inflammation and fibrosis in the surrounding tissues are common. Presence of gastric mucosa has been reported very rarely.4
Histologically, cutaneous bronchogenic cysts may be erroneously diagnosed as cystic mature teratoma or as a heterotopia, especially ectopic salivary tissue. Differential diagnosis also includes other cutaneous glandular cysts and skin appendageal cysts (table 1). Immunohistochemistry with TTF-1 may be helpful.
Awareness of this rare entity and its histological and clinical features may assist in making the correct diagnosis.
Clinical presentation is variable and may present as sinuses, cystic nodules or papillomatous growth. Occasionally, the cystic lesion drains a clear or mucinous fluid.
Bronchogenic cyst should be included in the differential diagnosis of cystic and nodular skin lesions on the upper chest, upper back and neck.