Skin Tumors Practice Questions

Q: A patient with a long history of betel nut chewing presents with a progressively enlarging mass protruding through the mouth. What is the IOC of likely diagnosis?

Edge biopsy. ***Edge biopsy (Incisional biopsy)*** - An **incisional biopsy** performed at the edge of the lesion is the **gold standard** (standard of care) for diagnosing oral malignancies, as it allows for the evaluation of both the **tumor tissue** and the **adjacent normal tissue** to assess the depth of invasion. - By sampling the **interface** of the lesion's border, the pathologist can confirm the diagnosis, determine the **histological grade**, and evaluate the **tumor margins** effectively. *Brush biopsy* - This technique, often referred to as **oral brush cytology** or **exfoliative cytology**, is primarily a **screening tool** rather than a diagnostic one. - It has a high rate of **false negatives** because it only collects superficial cells and cannot evaluate the **depth of invasion** or architectural patterns required for a definitive **malignancy** diagnosis. *Punch biopsy* - While useful for some superficial skin conditions, it is generally considered insufficient for deep, complex **oral masses** compared to an **incisional edge biopsy**. - There is a significant risk of **under-sampling** or missing the most representative area of the tumor, potentially leading to inaccurate staging or **misdiagnosis** of the malignancy.

Q: A patient is found to have a dark black lesion on the plantar surface of the foot. What is the most appropriate initial investigation?

Skin biopsy. ***Skin biopsy*** - A suspicious **pigmented lesion**, specifically one that is darkly pigmented on the acral surface (plantar surface of the foot), raises immediate concern for **acral lentiginous melanoma**. - An **excision biopsy** with an appropriate margin is the definitive diagnostic procedure to obtain a **histopathological diagnosis** and determine the **Breslow thickness**. *KOH mount* - This is utilized to identify **fungal infections** (dermatophytes) through the visualization of **hyphae** or yeast. - It is unsuitable for this case because a dark black lesion is suggestive of a **melanocytic neoplasm** rather than a fungal infection. *Gram stain* - This diagnostic tool is used for the rapid identification of **bacterial pathogens** in samples like pus, sputum, or blood. - It has no utility in the diagnosis of skin malignancies, as it provides no information regarding **cellular atypia** or **melanocytic lineage**. *Tzanck smear* - This test is employed to diagnose **herpesvirus infections** (like HSV or VZV) by looking for **multinucleated giant cells**. - It is not indicated for screening or diagnosing **dermal malignancies** such as melanoma.

Q: What is the dermatological sign associated with carcinoma of the stomach?

Acanthosis Nigrans. **Explanation:** **Acanthosis Nigricans (AN)** is the correct answer. While AN is most commonly associated with insulin resistance and obesity (Benign AN), its sudden, severe, and widespread onset in an older individual—often involving the palms (tripe palms) and mucous membranes—is a classic **paraneoplastic syndrome**. **Malignant Acanthosis Nigricans** is most frequently associated with **adenocarcinomas of the gastrointestinal tract**, with **stomach cancer** being the most common (approx. 50-60% of cases). It is thought to be mediated by tumor-secreted growth factors like Transforming Growth Factor-alpha (TGF-α) acting on epidermal EGF receptors. **Analysis of Incorrect Options:** * **A. Palmoplantar Keratoderma (PPK):** While acquired PPK can be paraneoplastic (Howel-Evans Syndrome), it is specifically linked to **Esophageal carcinoma**, not primarily the stomach. * **B. Acquired Ichthyosis:** This sudden onset of "fish-like" scaling in adulthood is most strongly associated with **lymphomas** (specifically Hodgkin’s Lymphoma), rather than gastric malignancies. * **D. Acrokeratosis Paraneoplastica (Bazex Syndrome):** This presents with psoriasiform plaques on acral sites (ears, nose, fingers). It is highly specific for squamous cell carcinomas of the **upper aerodigestive tract** (head, neck, and esophagus). **High-Yield Clinical Pearls for NEET-PG:** * **Tripe Palms:** When AN affects the palms, appearing velvety and rugose, it is 90% predictive of internal malignancy. If seen with AN, think **Stomach CA**; if seen alone, think **Lung CA**. * **Leser-Trélat Sign:** The sudden eruption of multiple Seborrheic Keratoses is another major cutaneous marker for **Gastric Adenocarcinoma**. * **Sister Mary Joseph Nodule:** A palpable nodule at the umbilicus representing metastasis from a pelvic or abdominal malignancy (most commonly Stomach CA).

Q: Which of the following lesions shows characteristic anagen, catagen, and telogen phases?

Keratoacanthoma. **Explanation:** **Keratoacanthoma (KA)** is a common, rapidly growing epithelial tumor that clinically and histologically resembles Squamous Cell Carcinoma (SCC). The hallmark of KA is its unique life cycle, which mimics the **hair follicle cycle**. It originates from the follicular infundibulum and progresses through three distinct stages: 1. **Proliferative phase (Anagen-like):** Rapid growth over 4–6 weeks, forming a dome-shaped nodule with a central keratinous plug. 2. **Stationary phase (Catagen-like):** Growth ceases, and the lesion stabilizes. 3. **Involutional phase (Telogen-like):** Spontaneous regression occurs over weeks to months, often leaving a puckered scar. **Analysis of Incorrect Options:** * **Basal Cell Carcinoma (BCC):** The most common skin cancer. It is characterized by slow growth, "pearly" borders, and telangiectasia. It does not undergo spontaneous regression or follow a follicular cycle. * **Leukoplakia:** A clinical term for a white patch on the mucosa that cannot be characterized as any other disease. It is a premalignant condition, not a follicular-derived tumor. * **Squamous Cell Carcinoma (SCC):** While KA is often considered a well-differentiated variant of SCC, true SCC is characterized by progressive, uncontrolled growth and invasion without a programmed involutional phase. **High-Yield NEET-PG Pearls:** * **Clinical Appearance:** "Volcano-like" appearance (dome-shaped with a central keratin plug). * **Histology:** Shows a central keratin-filled crater with "lips" or "buttresses" of overhanging epithelium. * **Syndrome Association:** Multiple keratoacanthomas are seen in **Muir-Torre Syndrome** (associated with internal malignancies) and **Grzybowski type** (generalized eruptive KAs). * **Management:** Despite spontaneous regression, surgical excision is usually recommended because it is difficult to distinguish KA from aggressive SCC.

Q: Xanthoma disseminatum is associated with which of the following conditions?

Diabetes Insipidus. **Explanation:** **Xanthoma disseminatum (XD)** is a rare, benign, non-Langerhans cell histiocytosis (non-LCH). It is characterized by the triad of **cutaneous xanthomas**, **mucosal involvement**, and **diabetes insipidus**. 1. **Why Diabetes Insipidus is correct:** The underlying pathophysiology involves the proliferation of histiocytes in various tissues. In approximately **40% of cases**, these histiocytic infiltrates involve the pituitary stalk or the hypothalamus. This leads to a deficiency in Vasopressin (ADH), resulting in **central Diabetes Insipidus**. The cutaneous lesions typically appear as small, reddish-brown to yellow papules and nodules symmetrically distributed over the face and flexural areas (axilla, groin). 2. **Why the other options are incorrect:** * **A. Down’s Syndrome:** While associated with certain dermatological conditions like syringomas and alopecia areata, it has no known association with XD. * **C. Lymphoma:** XD is a benign histiocytic proliferation. While some other xanthomatous conditions (like Necrobiotic Xanthogranuloma) are associated with paraproteinemias or malignancies, XD is not typically linked to lymphoma. * **D. Carcinoma of Pancreas:** There is no established clinical link between XD and pancreatic malignancy. **High-Yield Clinical Pearls for NEET-PG:** * **Normolipemic State:** Unlike most other xanthomas, Xanthoma Disseminatum occurs in patients with **normal lipid profiles**. * **The Triad:** Cutaneous lesions + Mucosal lesions (upper airway/oral) + Diabetes Insipidus. * **Montgomery’s Syndrome:** Another name for Xanthoma Disseminatum. * **Histology:** Features "Touton giant cells" and foamy macrophages (histiocytes) that are **S100 negative** and **CD68 positive** (confirming non-LCH origin).

Question 1

A patient with a long history of betel nut chewing presents with a progressively enlarging mass protruding through the mouth. What is the IOC of likely diagnosis?

Accepted Answer

Edge biopsy

Answer

Brush biopsy

Answer

Punch biopsy

Question 2

A patient is found to have a dark black lesion on the plantar surface of the foot. What is the most
appropriate initial investigation?

Accepted Answer

Skin biopsy

Answer

KOH mount

Answer

Gram stain

Answer

Tzanck smear

Question 3

What is the dermatological sign associated with carcinoma of the stomach?

Accepted Answer

Acanthosis Nigrans

Answer

Palmoplantar keratoderma

Answer

Acquired ichthyosis

Answer

Acrokeratosis paraneopiastica

Question 4

Which of the following lesions shows characteristic anagen, catagen, and telogen phases?

Accepted Answer

Keratoacanthoma

Answer

Basal cell carcinoma

Answer

Leukoplakia

Answer

Squamous cell carcinoma

Question 5

Xanthoma disseminatum is associated with which of the following conditions?

Accepted Answer

Diabetes Insipidus

Answer

Down's Syndrome

Answer

Lymphoma

Answer

Carcinoma of Pancreas

Skin Tumors — MCQs

Skin Tumors — MCQs

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