Interior, Deficiency/Empty, and Cold are classified as Yin in nature so in the context of the Eight Principles any pattern that is located in the Interior or is a Deficiency/Empty or is Cold will be Yin in Nature. As such Yin and Yang are general terms that can be used to describe most pathological conditions.
That being said Yin also has some conditions of its own, specifically Yin Deficiency and Yin Collapse.
Yin Deficiency conditions involve emaciation and weakness with wasting Heat symptoms, termed "false Yang". Patients that suffer from it are nutritionally depleted to the point that they begin to manifest Empty Heat symptoms, but in the context of Deficiency rather than Excess. For instance, a patient who is emaciated, runs on nervous energy, talks fast but peters out quickly, sleeps poorly, and has little stamina and low resistance is experiencing Empty Yin, or Yin Deficiency.
The main symptoms of Yin Deficiency are a feeling of Heat in the afternoon or evening, a dry throat at night, night sweating, thin body, a Floating-Empty pulse and a tongue without coating. Yin also moistens, hence the symptoms of Dryness such as dry throat and tongue.
Again, the above are only the general symptoms of Yin Deficiency, other symptoms depending on which Organ is mostly involved. The Organs most likely to suffer from Yin Deficiency are the Kidneys, Lungs, Heart, Liver and Stomach.
Other symptoms also depend on whether there is Empty Heat or not. If the Yin Deficiency is severe, after some time, Empty Heat will develop, causing (in addition to the above symptoms of Yin Deficiency) the following symptoms: a low-grade fever, a feeling of Heat in the evening, five-palm Heat and a Red tongue.
The main manifestations are abundant perspiration, skin hot to the touch, hot limbs, a dry mouth with desire to drink cold liquids in small sips, retention of urine, constipation, a Floating-Empty and Rapid pulse and a Red-Peeled, Short and Dry tongue.