Psammoma body

A psammoma body is a round collection of calcium, seen microscopically. The term is derived from the Greek word άμμος (ámmos), meaning "sand".

Cause
Psammoma bodies are associated with the papillary (nipple-like) histomorphology and are thought to arise from,
 * 1) Infarction and calcification of papillae tips.
 * 2) Calcification of intralymphatic tumor thrombi.

Association with lesions
Psammoma bodies are commonly seen in certain tumors such as:
 * Papillary thyroid carcinoma
 * Papillary renal cell carcinoma
 * Ovarian papillary serous cystadenoma and cystadenocarcinoma
 * Endometrial adenocarcinomas (papillary serous carcinoma ~3%-4%)
 * Meningiomas, in the central nervous system
 * Peritoneal and pleural mesothelioma
 * Somatostatinoma (pancreas)
 * Prolactinoma of the pituitary
 * Glucagonoma
 * Micropapillary subtype of lung adenocarcinoma

Benign lesions
Psammoma bodies may be seen in:
 * Endosalpingiosis
 * Psammomatous melanotic schwannoma
 * Melanocytic nevus

Appearance
Psammoma bodies usually have a laminar appearance, are circular, acellular and basophilic.