Psammoma bodies are seen in the following except ?
**Core Concept**
Psammoma bodies are small, concentrically laminated calcifications found in various types of neoplasms, particularly papillary thyroid carcinoma, serous ovarian cystadenocarcinoma, and meningiomas. They are formed through the deposition of calcium phosphate in the extracellular matrix of tumor cells.
**Why the Correct Answer is Right**
Psammoma bodies are a hallmark feature of papillary thyroid carcinoma, formed as a result of the interaction between tumor cells and the extracellular matrix. The deposition of calcium phosphate in these structures is mediated by the enzyme alkaline phosphatase, which is often elevated in papillary thyroid carcinoma. The presence of psammoma bodies is a significant diagnostic criterion for papillary thyroid carcinoma, especially when combined with other histological features such as papillary architecture and nuclear grooves.
**Why Each Wrong Option is Incorrect**
**Option A:** Psammoma bodies are not typically seen in renal cell carcinoma, which is characterized by a different set of histological features such as clear cell change and tubulopapillary architecture.
**Option B:** Psammoma bodies are not commonly associated with serous adenocarcinomas of the breast, which typically exhibit different histological features such as ductal or lobular architecture.
**Option C:** Psammoma bodies are not typically seen in glioblastoma multiforme, which is characterized by a different set of histological features such as pleomorphic cells and pseudopalisading necrosis.
**Clinical Pearl / High-Yield Fact**
Psammoma bodies are a classic example of a "tumor marker" that can aid in the diagnosis of certain neoplasms. They are formed through a complex interplay between tumor cells and the extracellular matrix, and their presence can have significant implications for patient management and prognosis.
**Correct Answer:** D.