**Core Concept**
Edema and shiny skin on the hands following a fracture and immobilization in a plaster of Paris (POP) cast suggest a condition related to venous stasis and fluid retention. The pathophysiology behind this condition involves impaired lymphatic drainage and increased venous pressure.

**Why the Correct Answer is Right**
The most likely diagnosis is Post-Phlebitic Syndrome (PPS), also known as Stasis Dermatitis, which is a complication of deep vein thrombosis (DVT). In this case, the immobilization of the arm in a POP cast leads to venous stasis, which can cause fluid to leak out of the capillaries and into the tissues, resulting in edema and shiny skin. The lymphatic vessels are unable to drain the excess fluid efficiently, exacerbating the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the clinical scenario described.
**Option B:** This option is incorrect because it does not account for the specific pathophysiology involved in the case.
**Option C:** This option is incorrect because it is a different condition altogether, unrelated to the effects of immobilization and venous stasis.

**Clinical Pearl / High-Yield Fact**
Remember that prolonged immobilization can lead to venous stasis, which can cause fluid retention and edema. This is a common complication in patients who have been bedridden or have been immobilized in a cast for an extended period.

**Correct Answer:** B. Stasis Dermatitis.