Pathology confirms the diagnosis of a pituitary tumour and classifies the tumour into a subtype. Subtype classification helps with prognosis and guides future therapy and follow up. A tumours subtype is determined by immunohistochemical staining for hormones, transcription factors, and other proteins.

Transcription Factor Subtype Clinical
Pit-1 Lactotroph tumours Hyperprolactinemia
Somatotroph tumours Acromegaly
Thyrotroph tumours Central Hyperthyroidism
Poorly differentiated pit-1 lineage tumour
(aka Silent subtype III adenoma)
Tpit Corticotroph tumours Cushing's
Crooke cell tumour Cushing's
SF-1 Gonadotroph tumour
None Null cell tumour
Unusual combination Plurihormonal pituitary tumour

Silent vs Null Cell

Atypical, Aggressive and Invasive Pituitary Tumours

Atypical adenomas are defined by the following histopathological criteria:

Invasiveness is often assessed by radiology and includes:

Aggressive pituitary tumours describe the tumours risk of recurrence and need for multiple surgeries and/or radiation. There are currently no agreed upon criteria for aggressive pituitary tumours. Predictors of aggressiveness include local invasion on radiology, tumour subtype, and past behaviour of the tumour.

Pituitary carcinoma is defined by the presence of cerebrospinal and/or systemic metastasis but there are no histopathological criteria.

Clinical Correlations Quick Reference


Densely granulated somatotroph adenoma (DGSA)
Sparsely granulated somatotroph adenoma (SGSA)
Mammosomatotroph adenoma
Mixed somatotroph and lactotroph adenoma
Plurihormonal GH secreting adenoma


Sparsely granulated lactotroph adenoma (SGLA)
Densely granulated lactotroph adenoma (DGLA)
Acidophil stem cell adenoma (ASCA)


Thyrotroph adenoma


Densely granulated corticotroph adenoma
Sparsely granulated corticotroph adenoma
Crooke-cell adenoma


Gonadotroph adenoma


Silent subtype III adenoma
Null cell adenoma
Crooke’s hyaline change