DPM Podiatric Pathology 2 — Questions and Answers
Question 1: Which histological finding is most characteristic of a plantar fibroma (Ledderhose disease)?
- Proliferating myofibroblasts within the plantar fascia (Correct answer)
- Malignant spindle cells with atypical mitoses
- Chronic inflammatory infiltrate with plasma cells
- Vascular proliferation with endothelial hyperplasia
Correct answer: Proliferating myofibroblasts within the plantar fascia
Plantar fibromas consist of proliferating myofibroblasts embedded in a collagen-rich stroma within the plantar fascia.
Question 2: A biopsy of a subungual lesion shows a vascular proliferation with a central fibrous core and surrounding epithelium. What is the most likely diagnosis?
- Glomus tumor
- Pyogenic granuloma
- Acquired digital fibrokeratoma (Correct answer)
- Subungual exostosis
Correct answer: Acquired digital fibrokeratoma
Acquired digital fibrokeratoma presents as a hyperkeratotic protrusion with a fibrovascular core covered by acanthotic epidermis.
Question 3: Which pathological change defines Charcot neuroarthropathy in its acute phase at the histological level?
- Osteoclastic bone resorption with periosteal new bone formation (Correct answer)
- Dense fibrous replacement of bone marrow
- Cartilaginous metaplasia of synovial tissue
- Dystrophic calcification of articular cartilage
Correct answer: Osteoclastic bone resorption with periosteal new bone formation
Acute Charcot arthropathy is characterized by osteoclast-mediated bone resorption driven by an autonomic neuropathy-induced inflammatory cascade.
Question 4: A 55-year-old diabetic patient has a heel ulcer with a biopsy showing fibrin exudate, granulation tissue, and no epithelialization. This corresponds to which wound healing phase?
- Inflammatory phase
- Proliferative phase (Correct answer)
- Remodeling phase
- Hemostatic phase
Correct answer: Proliferative phase
Granulation tissue formation is the hallmark of the proliferative phase, even when epithelialization is delayed as in chronic diabetic wounds.
Question 5: Which type of osteomyelitis is most commonly caused by hematogenous spread in children affecting the long bones of the foot?
- Type A (metaphyseal) (Correct answer)
- Type B (diaphyseal)
- Type C (epiphyseal)
- Type D (subperiosteal)
Correct answer: Type A (metaphyseal)
Hematogenous osteomyelitis in children preferentially affects the metaphysis due to its sluggish blood flow and lack of phagocytic lining cells.
Question 6: A 40-year-old runner presents with a mass over the second metatarsal head. Biopsy reveals a mucoid cyst with degenerating collagen and no true synovial lining. What is the diagnosis?
- Ganglion cyst (Correct answer)
- Synovial cyst
- Epidermal inclusion cyst
- Bursitis with synovial metaplasia
Correct answer: Ganglion cyst
Ganglion cysts arise from myxoid degeneration of connective tissue and lack a true epithelial or synovial lining, distinguishing them from synovial cysts.
Question 7: In osteosarcoma of the foot, which histological feature is pathognomonic?
- Malignant osteoid production by tumor cells (Correct answer)
- Cartilaginous lobules with endochondral ossification
- Fibrous stroma with herringbone pattern
- Giant cells with surrounding mononuclear cells
Correct answer: Malignant osteoid production by tumor cells
Osteosarcoma is defined by the direct production of malignant osteoid (immature bone matrix) by neoplastic cells.
DPM Podiatric Pathology 2
Which histological finding is most characteristic of a plantar fibroma (Ledderhose disease)?