The histopathological image provided, likely from a uterine mass, demonstrates a proliferation of spindle cells arranged in interlacing fascicles. The nuclei are elongated with blunt ends, and there is abundant eosinophilic cytoplasm. Mitotic activity appears low, and there is no significant nuclear atypia. Based on these findings, what is the most likely diagnosis?

Explanation

## Image Findings * Proliferation of **spindle-shaped cells**. * Cells arranged in **interlacing fascicles** (bundles running in different directions). * Nuclei are **elongated, blunt-ended, or cigar-shaped**. * Abundant **eosinophilic cytoplasm**. * **Low mitotic activity** and **minimal nuclear atypia** (no significant pleomorphism or hyperchromasia) visible at this magnification. ## Diagnosis **Key Point:** The image shows characteristic features of a **uterine leiomyoma**, specifically bundles of bland spindle cells with blunt-ended nuclei arranged in interlacing fascicles. Uterine leiomyomas, also known as fibroids, are benign smooth muscle tumors of the uterus. Their classic microscopic appearance includes well-demarcated bundles of smooth muscle cells that intersect at various angles. The individual cells have elongated, cigar-shaped nuclei with blunt ends and abundant eosinophilic cytoplasm. Mitotic figures are typically rare (<5 mitoses per 10 high-power fields), and there is an absence of significant nuclear atypia or coagulative necrosis. ## Differential Diagnosis | Feature | Uterine Leiomyoma | Leiomyosarcoma | Endometrial Stromal Sarcoma | | :------------------ | :---------------------------------------------- | :-------------------------------------------------------- | :-------------------------------------------------------- | | **Cellularity** | Moderate | High | Moderate to high | | **Arrangement** | Interlacing fascicles | Fascicles, often haphazard, infiltrative | Uniform cells, often around prominent arterioles | | **Nuclear Features**| Elongated, blunt-ended (cigar-shaped), bland | Marked atypia, pleomorphism, hyperchromasia | Small, uniform, oval to spindle, bland | | **Mitotic Activity**| Low (<5/10 HPF) | High (>10/10 HPF) | Variable, often low to moderate | | **Necrosis** | Infrequent, hyaline degeneration common | Coagulative tumor cell necrosis often present | Geographic necrosis can be seen | | **Cytoplasm** | Eosinophilic | Eosinophilic | Scant, pale | ## Clinical Relevance **Clinical Pearl:** Uterine leiomyomas are the most common benign tumors in women, often presenting with abnormal uterine bleeding, pelvic pressure, or infertility. They are hormonally responsive, growing during reproductive years and often regressing after menopause. ## High-Yield for NEET PG **High-Yield:** The histological triad for diagnosing leiomyosarcoma (to differentiate from leiomyoma) includes **nuclear atypia, mitotic activity (>10 mitoses/10 HPF), and coagulative tumor cell necrosis**. **Key Point:** Leiomyomas are typically well-circumscribed, while leiomyosarcomas are often infiltrative. ## Common Traps **Warning:** Differentiating a cellular leiomyoma or atypical leiomyoma from a low-grade leiomyosarcoma can be challenging and requires careful evaluation of mitotic activity, nuclear atypia, and presence of necrosis. The image provided clearly shows bland features, ruling out malignancy. ## Reference [cite:Robbins & Cotran Pathologic Basis of Disease, 10th Ed, Ch 22]