I'm not an author but it's a nice read 
Now, without viewing you, speaking to you, or hearing any of your symptoms, I can (statistically speaking) assure you that you do not have Gynecomastia. The frequency of post-pubertal Gynecomastia is estimated to be less than 10% of the male population; approximately 50% of pubertal boys may experience some form of Gynecomastia.
Further, a very small amount of physician-approached, post-pubertal, clinically defined Gynecomastia is drug induced. So, more than likely, you do not have 'Gyno', as it is known on the boards.
This begs the question, however: what is Gynecomastia? This thread is going to address that question, address the corollary "what is not Gynecomastia", as well as reviewing pertinent treatments of the affliction.
Table of Contents:
I. What is Gynecomastia
II. What is Not Gynecomastia
III. Popular and Proven Treatments
I. What is Gynecomastia
Clinically defined Gynecomastia is a benign enlargement of the mammary gland component of the male breast; the extreme proliferation of glandular tissue must occur to be clinical Gynecomastia. Most often, this proliferation is accompanied by pectoral adipose tissue, but the conditions are not mutually inclusive. Note: I will repeat this many times throughout this thread, without glandular tissue, it is not Gynecomastia. While Gynecomastia is most often unilateral, it can be bilateral as well.
From: Gynecomastia
Quote:
Types of Gynecomastia:
Type I: Benign adolescent hypertrophy
Physiologic discoid subacute mass
Resolves spontaneously
Type II: Physiologic gynecomastia - Generalized enlargement to greater degree
Type III: Obesity simulates gynecomastia
Type IV: Pectoral muscle hypertrophy
Marshall & Tanner Stages of breast enlargement/ development
[Adapted from Marshall WA, Tanner JM. Variations in pattern of pubertal changes in girls. Arch Dis Child 1969: 44:2291-303.]
Stage 1: Preadolescent; only papillae are elevated.
Stage 2: Breast bud and papilla are elevated and a small mount is present; areola diameter is enlarged.
Stage 3: Further enlargement of breast mound; increased palpable glandular tissue.
Stage 4: Areola and papilla are elevated to form a second mound above the level of the rest of the breast.
Stage 5: Adult mature breast; recession of areola to the mound of breast tissue, rounding of the breast mound, and projection of only the papilla are evident.
Causes
The causes of Gynecomastia in its three most often experienced stages - infancy, adolescence, and the elderly - are rarely identified on a case-by-case basis. However, in respects to the current audience, the use of a wide-range of hormonal compounds can cause the enlargement of the glandular component of the male breast.
While an in-depth discussion of hormonal feedback loops, and ER/PR receptor and receptor subtype expression is a far too robust discussion for this thread, it is needless to say hormones are not tinker toys - that is, removing and/or introducing and/or modifying one (or one set) of hormones most likely will remove and/or introduce and/or modify your existing hormones. Such hormonal fluctuations can cause a new case, or exacerbate and existing case, of Gynecomastia.
Diagnosis
Here is where I repeat the take-home lesson from this thread: without glandular proliferation (i.e., enlargement of the mammary gland) it is not Gynecomastia.
In order to ascertain whether or not you have Gynecomastia, there are three major procedures to conduct:
1) Conduct a self-breast examination - note their overall consistency and shape. Conduct the examination in front of a mirror in order to gain a perspective of the chest as a whole. True Gynecomastia will be characterized by an altered morphology of the chest; such a condition is not an "I wonder" condition. If you have it, you will notice. If your breast size is greater than 5cm (macromastia, or 'large breast) you most likely have physiologic, or pathologic Gynecomastia.
2) Lie flat on your back, and place one thumb on either side of the nipple. Slowly bring your thumbs together, applying pressure inwards to the chest. If you have Gynecomastia, your thumbs will press against hard, fibrous, and rubbery glandular tissue; if you do not, your thumbs will meet at the nipple. If fibrous tissue is noted, it should be very tender, and painful to the touch.
3) While this can be conducted with number one, a separate test should be conducted to note for oily discharge from the nipple. If Gynecomastia is present, the discharge should be easily excreted; the constant aggravation of breast tissue may produce discharge even in pseudogynocomastia (if it does not come on first squeeze, stop touching it).
If you not either of these indicative symptoms, you may have Gynecomastia, and at which point you should contact a physician for referral; if you did not note either of these symptoms, continue onto the next section.
II. What is Not Gynecomastia
Now that we have ascertained what Gynecomastia is, we must now differentiate what is not.
Conditions Which Are Not Gynecomastia
1) 'Puffy' or 'sensitive' nipples. If you note a very slight inflammation and tenderness to your nipples while using hormonal products, do not be alarmed. It is very possible estrogen has become bound to ERs under your nipples, but this is not necessarily Gynecomastia. A mere reduction of circulating estrogen via an AI, or spot-specific treatment via a SERM, will more often than not eradicate such a symptom.
2) The existence of a 'pebble' under or around the nipple. If you detect small fibrous 'pebbles' directly under your nipple, this very well may be the precursor to Gynecomastia. However, at such a time where the 'pebble' is newly developed, minor treatment with an effective SERM or AI will most likely remove the tissue.
3) Excess adipose tissue in and around the pectoral area. Remember: without glandular tissue, it is not Gynecomastia. While adipose tissue most often accompanies Gynecomastia, it is not Gynecomastia in-and-of-itself; such adipose not accompanied by glandular tissue is what is known as, 'pseudogynecomastia'.
Pseudogynecomastia
Pseudogynecomastia is any one, or more of the conditions listed above without the proliferation of glandular tissue. It is most likely caused by the stimulation of estrogen or progesterone receptor or receptor subtypes in the breast area; in most cases, as said earlier, they can be remedied by using systemic or breast-specific estrogen controlling remedies.
III. Popular and Proven Treatments
A quick research search will reveal that invasive surgery is regarded as the only manner to remove permanent glandular tissue; however, recent studies have revealed the use of aromatase inhibitors such as Letrozole, or SERMs such as Tamoxifen Citrate, can eradicate proliferated glandular tissue.
In cases of long or unknown duration, or where macromastia beyond increased glandular tissue is noted, surgery is almost always required. With that being said, most treatment centers and studies noted that tissue under 36 months duration can be treated non-surgically.
The two most common classes of Gynecomastia treatments are SERMs (Selective Estrogen Receptor Modulators) which are breast-specific, and AI (Aromatase Inhibitors) which are systemic, and lower serum levels of E1 and E2.
The most common SERMs are:
Tamoxifen
Raloxifen
Toremifene
Clomid
The most common Aromatase Inhibitors are:
Letrozole
Anastrozole