A 58-year-old male smoker (40 pack-years) presents with persistent cough and haemoptysis for 3 weeks. Chest X-ray shows a 4 cm peripheral nodule in the right lower lobe with irregular borders. CT chest reveals no mediastinal lymphadenopathy. Bronchoscopy with biopsy shows malignant cells arranged in nests with prominent desmoplastic stromal reaction and keratinization. What is the most likely histological type of lung cancer?

Question

Accepted Answer

B. Squamous cell carcinoma. ## Histopathological Diagnosis

**Key Point:** The combination of keratinization and desmoplastic stromal reaction (fibrous tissue response) is pathognomonic for squamous cell carcinoma of the lung.

## Clinical & Pathological Features of Squamous Cell Carcinoma

| Feature | Squamous Cell | Adenocarcinoma | Large Cell | Small Cell |
|---------|---------------|----------------|------------|------------|
| **Keratinization** | Present (hallmark) | Absent | Absent | Absent |
| **Desmoplasia** | Prominent | Mild | Absent | Absent |
| **Smoking association** | Very strong (90%) | Moderate | Strong | Very strong |
| **Location** | Central/hilar | Peripheral | Peripheral | Central |
| **Bronchoscopy finding** | Endobronchial lesion | Distal/parenchymal | Rare | Central |

## Pathological Architecture

**High-Yield:** Squamous cell carcinoma shows:
1. Nests of polygonal cells with clear cytoplasm
2. Intercellular bridges (desmosomes) — sign of squamous differentiation
3. Keratin pearl formation (concentric layers of keratinized cells)
4. Desmoplastic response (abundant collagen deposition by fibroblasts)

## Clinical Context

**Clinical Pearl:** This patient's presentation is classic for squamous cell carcinoma:
- Heavy smoking history (40 pack-years)
- Central/hilar location tendency (though can be peripheral)
- Haemoptysis (from endobronchial ulceration)
- Desmoplastic stromal reaction visible on histology

**Mnemonic: DESK** — Desmoplasia, Endobronchial location, Smoking (strong), Keratinization

## Why This Matters

**Warning:** Do not confuse squamous cell carcinoma with adenocarcinoma. Adenocarcinoma shows mucin production and glandular differentiation, NOT keratinization. Large cell carcinoma lacks both keratinization and glandular features — it is a diagnosis of exclusion.

![Lung Cancer — Non-Small Cell diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3720.webp)

Answer

A. Large cell carcinoma

Answer

C. Small cell carcinoma

Answer

D. Adenocarcinoma

Explanation

Histopathological Diagnosis

Clinical & Pathological Features of Squamous Cell Carcinoma

Pathological Architecture

Clinical Context

Why This Matters

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Feature	Squamous Cell	Adenocarcinoma	Large Cell	Small Cell
Keratinization	Present (hallmark)	Absent	Absent	Absent
Desmoplasia	Prominent	Mild	Absent	Absent
Smoking association	Very strong (90%)	Moderate	Strong	Very strong
Location	Central/hilar	Peripheral	Peripheral	Central
Bronchoscopy finding	Endobronchial lesion	Distal/parenchymal	Rare	Central