Albino Wyrm
Large Dragon (Cold, Earth)
Hit Dice: 7d12+28 (73 hp)
Initiative: +4
Speed: 40 ft. (8 squares), burrow 10 ft., swim 20 ft.
Armor Class: 24 (-1 size, +15 natural), touch 9, flat-footed 24
Base Attack/Grapple: +7/+17
Attack: Bite +12 melee (3d6+9) or tail-slap +12 melee (1d8+9)
Full Attack: Bite +12 melee (3d6+9)  and 2 claws  +10 melee (1d6+3) and tail-slap +10 melee (1d8+9)
Space/Reach: 10 ft./5 ft. (10 ft. with bite, 20 ft. with tail-slap)
Special Attacks: Breath weapon, constrict 1d8+9, improved grab, powerful bite, swallow whole
Special Qualities: Blindsense 120 ft., darkvision 120 ft., madness, spell resistance 17
Saves: Fort +9, Ref +5, Will +7
Abilities: Str 23, Dex 10, Con 19, Int 14, Wis 11, Cha 15
Skills: Appraise +7, Escape Artist +8, Knowledge   (dungeoneering) +7, Hide +6, Intimidate +10, Jump +16, Listen +10, Move  Silently +10, Spot +10, Use  Magic Device +10, Swim +14, Survival +2 (+4  underground), Use Rope +0 (+2 binding  foes)
Feats: Blind-Fight (B),  Improved Initiative, Multiattack, Power Attack
Environment: Subterranean
Organization: Solitary
Challenge Rating: 7
Treasure: standard coins, double goods, triple items
Alignment: Always neutral evil
Advancement: 8-14 HD (Large); 15-29 HD (Huge); 30+ HD (Gargantuan)
Level Adjustment: —
 A gaunt, sinewy dragon with over-sized jaws and vestigial,  translucent wings. It has mottled white scales, dirt brown talons and  eyes that seem red with madness.
The ancestors of albino wyrms may have been surface dragons who became lost in the unfathomable depths of the Underdark. If this is so, their offspring have become stunted creatures who lack the intelligence, flight and spellcasting ability of a true dragon. Albino wyrm are afflicted with some form of hereditary madness and are barely able to express a sane thought.
Few places in the Underdark hold enough food to nourish an albino wrym for long, so they rarely form permanent lairs. Most of these dragon-kin spend their lives wandering from hunting ground to hunting ground carrying what treasure they possess, resting in dens, and moving on once the prey nearby is depleted. The only wealth albino wyrms truly value are magic items, especially items that aid them in hunting. They often wear jewelery, although it may not be on the intended body part. Thus, a wealthy wyrm may wear a crown around the tail, rings on its claws, and a bracelet on a wingtip. Less "worthy" valuables, such as coins, are usually carelessly strewn around their temporary den.
A typical albino wyrm is 20 to 25 feet long, including about 10 feet of tail.
Albino wyrms can speak Draconic, but their minds are so deranged they cannot hold a coherent conversation. 
Combat
Albino wyrms, while intelligent, are  insanely ferocious, fighting  more like cunning animals than devious  dragons.  They rely on stealth to ambush prey, any may use their  burrowing ability to attack from unexpected directions, such as bursting  out of an apparently solid wall. The wyrm usually attacks first with  its breath weapon then leaps into melee, attempting to  swallow  vulnerable spellcasters when possible. Food is so scarce in the  Underdark that albino wyrms rarely stop attacking prey once they find  it, although they are not foolish enough  to disdain retreat when  necessary.
Breath Weapon (Ex): 40-ft. cone, damage 6d6 cold, Reflex DC 17  half. An albino wyrm can use its breath weapon once every 1d4 rounds. The save DC is Constitution-based. 
Constrict (Ex): On a successful grapple check, an albino wyrm automatically deals bludgeoning damage equal to its tail-slap attack.
Improved Grab (Ex): To use this ability, an albino wyrm must hit with its bite attack. It can  then attempt to start a grapple as a free action without provoking an  attack of opportunity. If it wins the grapple check, it establishes a  hold and can constrict or swallow whole. 
 Madness (Ex): Albino wyrms use their Charisma modifier on Will  saves  instead of their Wisdom modifier, and have immunity to confusion  and  insanity effects.
Powerful Bite (Ex): An albino wyrm adds 1½ times its Strength bonus to its bite attack damage.
Swallow Whole (Ex): An albino wyrm can try to swallow a grabbed opponent smaller than itself by making a successful grapple check. Once inside, the opponent  takes 3d6+9 points of crushing damage plus 6 points of acid damage per  round from the wyrm's gizzard. A swallowed creature can cut its way out  by using a light slashing or piercing weapon to deal 25 points of  damage to the gizzard (AC 17). Once the creature exits, muscular action  closes the hole; another swallowed opponent must cut its own way out. A Large albino wyrm's interior can hold 1 Medium-sized, 4 Small, 16 Tiny, 64 Diminutive or 256 Fine opponents.
Skills: An albino wyrm has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line. 
Advanced Albino Wyrms
Albino wyrms of Huge size or larger gain the Tail Sweep special attack.
Tail Sweep (Ex): An albino wyrm  of at least Huge size can  sweep its tail as a standard action, affecting a  half-circle with a  radius equal to the Reach of its tail-slap attack.  All creatures within  the swept area that are up to three size categories  smaller than the wyrm automatically take damage equal  to the wyrm's  tail-slap attack. Affected creatures can attempt Reflex  saves to take  half damage. The save DC is Strength-based.     
Originally appeared in Dragon 227 (1996)
If we were using age categories, they'd go like this:
2-3 HD Small "Wyrmling"
4-6 HD Medium-sized "Juvenile"
7-14 HD Large "Adult"
15-29 HD Huge "Old"
30+ HD Gargantuan "Wyrm"