Sclerosing Haemangioma

Epidemiology and Etiology:

• Middle aged adults (median 46y)
• Females 80%
• East Asia > Western countries

Common sites:

• Peripheral lung
• May occasionally spread to regional lymph nodes (1%)
• Mediastinum primary rarely

Gross features:

• Solitary mostly
• 0.3-8.0cm
• Solid, occasionally with cystic degeneration
• Gray to tan-yellow with foci of hemorrhage
• Peripheral lung
• May involve mediastinum
• Endobronchial polyp rarely
• CXR:
• Solitary, well-circumscribed mass
• Calcified occasionally
• Cystic occasionally
• Marked contrast enhancement
• Hemorrhagic component on MRI

Histologic features:

• 2 cell types:
• Round stromal cells
• Surface cells
• Round cells:
• Small
• Well-defined borders
• Central round to oval bland nucleus
• Focal mild to marked nuclear atypia maybe
• Fine dispersed chromatin
• Absence of distinct nucleoli
• Low mitoses (< 1 per 10HPF usually)
• Eosinophilic cytoplasm
• May be foamy or vacuolated or signet ring
• Surface cells:
• Cuboidal
• Morphology of bronchial epithelium and activated type II pneumocytes
• May be multinucleated
• Cytoplasm may be clear, vacuolated, foamy
• Intranuclear inclusions maybe
• Focal mild to marked nuclear atypia maybe
• Papillary pattern:
• Complex papillae lined by cuboidal surface cells
• Stalk contains round cells
• Sclerotic or myxoid
• Sclerotic pattern:
• Dense foci of hyaline collagen at periphery of hemorrhagic areas or within paipillary stalks or in solid areas
• Solid pattern:
• Sheets of round cells with scattered cuboidal surface cells forming small tubules
• Hemorrhagic pattern:
• Large blood-filled spaces lined by epithelial cells
• Hemosiderin, foamy macrophages, cholesterol clefts
• May be surrounded rarely by granulomatous and chronic inflammation
• Calcifications may be psammoma-like
• Neuroendocrine tumourlets rarely
• Cytology:
• Moderately cellular
• Dual cell population
• Round cells:
• Small
• Round or spindle-shaped
• Granular cytoplasm
• Uniform nuclei
• May be atypical but absence of nucleoli
• Arranged in cohesive papillary clusters or in flat pavement-type orientation
• Hyalinized stromal tissue fragments maybe
• Foamy macrophages, hemosiderin, red cells in background

Immunophenotype:

Marker:	Sensitivity:	Specificity:
TTF-1 (surface and round cells)
EMA (surface and round cells)
CK (only surface cells)
Surfactant apoprotein A (surface cells)

Molecular features:

• Clonal population (both cell types same clone)

Other features:

• Clinically benign
• No significance of mediastinal lymph node involvement

References:

•  Essentials of Anatomic Pathology, 2^nd Ed (2006)