**Core Concept**
HMB 45 is a monoclonal antibody-based immunohistochemical marker used to identify certain types of tumors. It reacts with an antigen present in melanocytic lesions, particularly melanomas and neurofibromas.

**Why the Correct Answer is Right**
HMB 45 targets a high-molecular-weight melanoma-associated antigen (HMW-MMA), which is a glycoprotein present in melanocytes and their neoplastic counterparts. This antigen is expressed in approximately 90% of melanomas, making HMB 45 a useful marker for the diagnosis of melanocytic lesions. The antibody reacts with this antigen in a paraffin-embedded tissue section, allowing for the identification of melanoma cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because HMB 45 is not typically used to identify carcinomas, such as those of breast or lung origin. While some carcinomas may express melanocyte markers, HMB 45 is not a reliable marker for these tumors.
**Option B:** This option is incorrect because HMB 45 is not used to identify lymphomas. Lymphomas are typically identified using markers such as CD20, CD3, or CD45, rather than melanocyte-specific markers like HMB 45.
**Option C:** This option is incorrect because HMB 45 is not used to identify sarcomas in general. While some sarcomas may express melanocyte markers, HMB 45 is not a reliable marker for these tumors.

**Clinical Pearl / High-Yield Fact**
When interpreting immunohistochemical stains, it's essential to consider the specific antigen being targeted and the type of tumor being diagnosed. HMB 45 is a valuable marker for identifying melanocytic lesions, but it's not a substitute for thorough clinical evaluation and histopathological examination.

**Correct Answer: D. Melanomas**