**Question:** Anaplastic cells often display the following morphologic features except --------.

A. Increased cellular pleomorphism
B. Narrowed and elongated nuclei
C. Nuclear pseudoinclusions
D. Nucleoli that are prominent

**Core Concept:** Anaplastic cells are malignant cells that exhibit marked cytological atypia, which is a measure of cell differentiation and differentiation potential. These cells are characterized by various morphologic features, including increased cellular pleomorphism, narrowed and elongated nuclei, prominent nucleoli, and nuclear pseudoinclusions.

**Why the Correct Answer is Right:** Option B, "Narrowed and elongated nuclei," is not a characteristic feature of anaplastic cells. While elongated nuclei might be observed, the nuclear shape should be irregular and not uniformly narrow. This feature helps differentiate between malignant (anaplastic) cells and benign conditions with elongated nuclei, such as in lymphocytes.

**Why Each Wrong Option is Incorrect:**

A. Increased cellular pleomorphism: Anaplastic cells show increased cellular pleomorphism, making this feature correct and not an exception.

C. Nuclear pseudoinclusions: Anaplastic cells often display nuclear pseudoinclusions, which are irregular nuclear inclusions that mimic cytoplasmic inclusions. This feature is associated with malignancy and is not an exception.

D. Prominent nucleoli: Prominent nucleoli can be observed in some malignant cells, including anaplastic cells. However, this feature is not a universal exception, as the size and number of nucleoli can vary in different types of malignancies.

**Clinical Pearl:** The differentiation between benign and malignant cells based on nuclear shape alone can be challenging. However, a combination of features, including pleomorphism, irregularity, and the presence of pseudoinclusions, helps differentiate between benign and malignant cells, including anaplastic cells. It is essential for accurate diagnosis and treatment planning.