In most cases, the first three fuse at 15–18 years, whereas the base part fuses to the scapular spine at 12 years. However, in between 1% and 15% of cases, this osseous union fails and the acromion remains separate as an accessory bone. This condition is referred to as os acromiale, but rarely causes pain. Earlier estimates of its prevalence were as low as 1.4%, and this higher estimate was made by Sammarco in the year 2000, based on radiographic and anatomical studies.Four types of os acromiale can be distinguished:
A non-union between the meso- and meta-acromia, the most common or typical os acromiale
A non-union between the pre- and meso-acromia
A non-union between the pre- and meso-acromia; and between the meso- and meta-acromia, atypical
A non-union between the pre- and meso-acromia; between the pre- and meso-acromia; and between the meta- and basi-acromiaThis feature was common in skeletons recovered from the Mary Rose shipwreck: it is thought that in those men, much archery practice from childhood on with the mediaeval war bow (which needs a pull three times as strong as the modern standard Olympic bow) pulled at the acromion so much that it prevented bony fusion of the acromion with the scapula. Although historically regarded as an incidental finding, the os acromiale may occasionally produce symptoms from subacromial impingement or instability at the site of non-union. In people with symptoms of  os acromiale, dynamic ultrasound sometimes shows hypermobility in the area during shoulder movement, or graded compression with the probe.
FDA approved treatments include the following:
(1999) Denileukin diftitox (Ontak)
(2000) Bexarotene (Targretin) a retinoid
(2006) Vorinostat (Zolinza) a hydroxymate histone deacetylase (HDAC) inhibitor
(2009) Romidepsin (Istodax) a cyclic peptide histone deacetylase (HDAC) inhibitor
(2018) Poteligeo (mogamulizumab-kpkc)Histone deacetylase (HDAC) inhibitors are shown to have antiproliferative and cytotoxic properties against CTCL.Other (off label) treatments include:

In 2010, the U.S. Food and Drug Administration granted orphan drug designation for naloxone lotion as a treatment for pruritus in cutaneous T-cell lymphoma to a pharmaceutical company called Elorac. Epidemiology
Of all cancers involving lymphocytes, 2% of cases are cutaneous T cell lymphomas. CTCL is more common in men and in African-American people. The incidence of CTCL in men is 1.6 times higher than in women.There is some evidence of a relationship with human T-lymphotropic virus (HTLV) with the adult T-cell leukemia/lymphoma subtype. No definitive link between any viral infection or environmental factor has been definitely shown with other CTCL subtypes. See also
Cutaneous B-cell lymphoma
List of cutaneous conditions

References
External links

DermNet dermal-infiltrative/cutaneous-t-cell-lymphoma