**Question:** A 35 year old lady complains dysphagia, Raynaud's phenomenon, sclerodactyly. Investigations show antinuclear antibody. The likely diagnosis is:

A. Systemic sclerosis
B. Systemic lupus erythematosus
C. Sjögren's syndrome
D. Scleroderma

**Correct Answer:** A. Systemic sclerosis

**Core Concept:**
Systemic sclerosis (SSc) is a connective tissue disease that primarily affects the skin and internal organs. It is characterized by excessive fibrosis (scarring) of the skin and internal organs, leading to increased vascular resistance and impaired organ function. The disease is classified into two subtypes: limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc). The main features that distinguish the two subtypes are the extent of skin involvement and organ involvement.

**Why the Correct Answer is Right:**
In this case, the patient presents with dysphagia, Raynaud's phenomenon, and sclerodactyly (thickened, hardened fingertips). These symptoms are hallmarks of Systemic sclerosis. Dysphagia is due to esophageal involvement, Raynaud's phenomenon is a consequence of vascular abnormalities, and sclerodactyly is a result of skin fibrosis in the fingers. Additionally, the presence of antinuclear antibodies in the patient's blood confirms the diagnosis.

**Why Each Wrong Option is Incorrect:**

A. Systemic lupus erythematosus (SLE) typically presents with a more widespread involvement of the skin, mucous membranes, and internal organs. Antinuclear antibodies are also present in SLE, but the clinical features mentioned are more consistent with SSc.

B. Systemic sclerosis (SSc) is the correct diagnosis. SLE is a different connective tissue disease and does not present with Raynaud's phenomenon and sclerodactyly.

C. Sjögren's syndrome (SS) is a different autoimmune disorder affecting the exocrine glands, particularly the salivary and lacrimal glands. It is characterized by dryness of the eyes and mouth. The symptoms mentioned in the question are more consistent with SSc.

D. Scleroderma is a term used for systemic sclerosis. The patient's symptoms and laboratory findings (antinuclear antibodies) align more closely with the diagnosis of SSc.

**Clinical Pearl:**

Systemic sclerosis is a complex and multifactorial disease. The pathogenesis involves autoimmune response, leading to fibrosis (scarring) of the skin and internal organs. The Raynaud's phenomenon, sclerodactyly, and antinuclear antibodies are hallmark features of SSc, making this the correct diagnosis in this case.