Bone and Soft Tissue Pathology Practice Questions

Q: The differential diagnosis of a lesion, histologically resembling a giant cell tumor in the small bones of the hands or feet, includes all of the following except:

Fibrosarcoma. **Explanation:** The core of this question lies in identifying lesions that contain **Giant Cells** on histology, which can mimic a Giant Cell Tumor (GCT). **Why Fibrosarcoma is the Correct Answer:** Fibrosarcoma is a malignant tumor of mesenchymal origin characterized by a "herringbone" pattern of spindle-shaped fibroblasts. Crucially, it **does not typically contain multinucleated giant cells** as a primary histological feature. Therefore, it is not a standard differential diagnosis for a GCT-like lesion. **Analysis of Incorrect Options (Differential Diagnoses of GCT):** * **Aneurysmal Bone Cyst (ABC):** These are common in small bones and histologically show blood-filled spaces separated by fibrous septa containing numerous multinucleated giant cells. * **Osteosarcoma:** Specifically, the **Telangiectatic variant** of osteosarcoma contains large blood-filled spaces and numerous giant cells, making it a dangerous mimic of GCT. * **Hyperparathyroidism (Brown Tumor):** This is the most classic "mimicker" of GCT. Histologically, Brown tumors are virtually indistinguishable from GCTs as they contain abundant giant cells. Clinical correlation with serum calcium and PTH levels is essential. **NEET-PG High-Yield Pearls:** 1. **GCT (Osteoclastoma):** Occurs in the **epiphysis** after skeletal maturity (20-40 years). It shows a "Soap Bubble" appearance on X-ray. 2. **Giant Cell Rich Lesions:** Remember the mnemonic **"G-A-B-O"**: **G**iant Cell Tumor, **A**neurysmal Bone Cyst, **B**rown Tumor (Hyperparathyroidism), and **O**steoblastoma/Osteosarcoma (Telangiectatic). 3. **Location:** While GCT is common in the distal femur/proximal tibia, when a "GCT-like" lesion appears in the **small bones of hands/feet**, always rule out an ABC or a Brown Tumor first.

Q: Glomus tumors are most commonly seen in which of the following locations?

Finger. **Explanation:** **Glomus tumors** (glomangiomas) are benign, exquisitely painful tumors arising from the modified smooth muscle cells of the **glomus body**. The glomus body is a specialized arteriovenous anastomosis involved in thermoregulation. 1. **Why the Finger is Correct:** Glomus bodies are most densely concentrated in the distal portions of the digits, particularly in the **subungual (under the nail) region** of the fingers. These tumors typically present as a small, firm, blue-red nodule. Clinically, they are characterized by a classic triad: **paroxysmal pain, localized tenderness, and sensitivity to cold.** 2. **Why Other Options are Incorrect:** * **Liver, Adrenals, and Pituitary:** These organs do not contain glomus bodies. While vascular tumors can occur in these sites (e.g., hepatic hemangiomas), glomus tumors are specifically cutaneous or subcutaneous lesions of the extremities. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Derived from **Sucquet-Hoyer canals** (the arterial segment of the glomus body). * **Histology:** Characterized by nests of uniform, round "glomus cells" surrounding thin-walled vascular spaces. * **Immunohistochemistry (IHC):** Glomus cells are positive for **Alpha-Smooth Muscle Actin (α-SMA)** and Vimentin, reflecting their smooth muscle origin. They are negative for endothelial markers like CD31 (except in the vessel lining). * **Treatment:** Simple surgical excision is curative and provides immediate pain relief. * **Differential Diagnosis:** Must be distinguished from other painful skin tumors (mnemonic **LEND AN ARM**: Leiomyoma, Eccrine spiradenoma, Neuroma, Dermatofibroma, Angiolipoma, Neurilemmoma, **Glomus tumor**).

Q: The odontogenic neoplasm, which is microscopically composed of loose, primitive-appearing connective tissue that resembles dental pulp, is known as _____.

Odontogenic myxoma. **Explanation:** The correct answer is **Odontogenic Myxoma**. This neoplasm is derived from the odontogenic ectomesenchyme (specifically the dental papilla, follicle, or periodontal ligament) [1]. **Why Odontogenic Myxoma is correct:** Microscopically, it is characterized by a **hypocellular** arrangement of stellate or spindle-shaped cells embedded in an abundant **mucoid/myxomatous extracellular matrix**. This appearance closely mimics the **primitive connective tissue of the dental pulp**. On imaging, it typically presents as a multilocular radiolucency with a characteristic **"soap bubble"** or **"honeycomb"** appearance, often showing "string-of-tennis-racket" bony trabeculations. **Why the other options are incorrect:** * **Odontoma:** These are hamartomas rather than true neoplasms [1]. They consist of mature enamel, dentin, cementum, and pulp tissue arranged either in a tooth-like shape (Compound) or a disorganized mass (Complex). * **Ameloblastoma:** This is an epithelial tumor, not mesenchymal [1]. It is characterized by islands of odontogenic epithelium with peripheral palisading cells (reverse polarity) and a central area resembling stellate reticulum. * **Ameloblastic Fibroma:** This is a mixed tumor (epithelial and mesenchymal). While it contains primitive-looking connective tissue, it must also feature islands and cords of odontogenic epithelium to satisfy the diagnosis. **NEET-PG High-Yield Pearls:** * **Histology Keyword:** "Stellate cells in a loose myxoid stroma." * **Radiology Keyword:** "Soap bubble" or "Tennis racket" appearance. * **Consistency:** Grossly, the tumor has a gelatinous or slimy consistency, making complete surgical removal difficult (high recurrence rate). * **Origin:** Derived from the **mesenchymal** component of the tooth germ [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Question 1

The differential diagnosis of a lesion, histologically resembling a giant cell tumor in the small bones of the hands or feet, includes all of the following except:

Accepted Answer

Fibrosarcoma

Answer

Aneurysmal bone cyst

Answer

Osteosarcoma

Answer

Hyperparathyroidism

Question 2

What is the most common site of rhabdomyosarcoma?

Accepted Answer

Orbit

Answer

Nasopharynx

Answer

Extremities

Answer

Hypopharynx

Question 3

Mutation in the GNAS1 gene is associated with which of the following conditions?

Accepted Answer

Fibrous dysplasia

Answer

Ossifying fibroma

Answer

Focal cementoosseous dysplasia

Answer

Periapical cementoosseous dysplasia

Question 4

Which of the following radiographic findings is associated with Paget’s disease?

Accepted Answer

Paget’s disease

Answer

Fibrous dysplasia

Answer

Hyperparathyroidism

Answer

Osteoma

Question 5

Carcinoma with predilection for metastasis to bones of hands and feet?

Accepted Answer

Bronchus

Answer

Prostate

Answer

Pelvis

Answer

Breast

Question 6

Glomus tumors are most commonly seen in which of the following locations?

Accepted Answer

Finger

Answer

Liver

Answer

Adrenals

Answer

Pituitary

Question 7

Perifasicular atrophy of muscle fibres is seen in which condition?

Accepted Answer

Dermatomyositis

Answer

Steroid myopathy

Answer

Inclusion body myositis

Answer

Viral myositis

Question 8

A 30-year-old man presents with a radiolucent lesion. Imaging reveals a hollow cavity without epithelial lining. What is the most probable diagnosis?

Accepted Answer

Hemorrhagic bone cyst

Answer

Aneurysmal bone cyst

Answer

Static bone cavity

Answer

Ameloblastoma

Question 9

Protein level more than 4-5 g/100ml is seen in all of the following except:

Accepted Answer

Odontogenic keratocyst (OKC).

Answer

Dentigerous cyst.

Answer

Radicular cyst.

Answer

None of the above.

Question 10

The odontogenic neoplasm, which is microscopically composed of loose, primitive-appearing connective tissue that resembles dental pulp, is known as _____.

Accepted Answer

Odontogenic myxoma

Answer

Odontoma

Answer

Ameloblastoma

Answer

Ameloblastic fibroma

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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