Granular parakeratosis, a benign condition, was first described in 1991 as a skin disease manifesting with erythematous hyperpigmented and hyperkeratotic papules and plaques of the cutaneous folds.  Granular parakeratosis is sometimes associated with pruritus. Granular parakeratosis has been associated with excessive use of topical preparations, in particular antiperspirants and deodorants; however, it has been found in persons who have not used such agents.
Granular parakeratosis is also associated with an occlusive environment, increased sweating, and, sometimes, local irritation. Some have linked it to obesity. New cases of granular parakeratosis continue to be reported involving different body regions.  Some suggest that granular parakeratosis has congenital links,  and others have considered if granular parakeratosis is a disease or a reactive process.  New cases are reported every year, and the disease is likely underdiagnosed. 
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The etiology of granular parakeratosis is uncertain, but Metze and Rütten  defended the hypothesis, first proposed by Northcutt et al,  that a basic defect exists in the processing of profilaggrin to filaggrin, which maintains the keratohyaline granules in the stratum corneum during cornification. Because granular parakeratosis has been associated with excessive use of topical preparations, an occlusive environment, increased sweating, and, sometimes, local irritation, some suggest that it is an allergic contact or irritant reaction.  Some patients who have manifested granular parakeratosis have not used topical preparations, and, thus, the causal linkage of granular parakeratosis to topical substances is unclear.
An interesting finding that mice that are deficient in caspase-14, an important protease necessary for the proper formation of a totally functional skin barrier, are more likely to develop parakeratosis may help elucidate the etiology of granular parakeratosis. 
In any case, the primary cause for granular parakeratosis remains unknown.
Only approximately 40 case reports of granular parakeratosis have been published, but it is likely more common than the number of case reports suggests. Scheinfeld and Mones  reviewed the diagnoses of 363,343 specimens submitted to the Ackerman Institute of Dermatopathology in New York over a 5-year period. Eighteen (0.005%) of 363,343 specimens were diagnosed with granular parakeratosis. Scheinfeld and Mones  concluded that if the incidence of granular parakeratosis among biopsy specimens is representative of its general prevalence among persons with cutaneous eruptions, granular parakeratosis is rare.
The dermatopathology reports of the DermatoHistologisches Labor Dr. H. Laaff were reviewed for the diagnosis of granular parakeratosis. From 2004-2007, 10 cases (7 women, 3 men) of granular parakeratosis were noted, for a frequency of 0.004%. The average patient age was 62 years (range 33-82 y). In women, granular parakeratosis manifested in submammary areas (4), axillae (2), and popliteal fossa; in men, granular parakeratosis manifested in the groin (2) and genital areas. 
Only rare case reports of granular parakeratosis are noted, but it is probably not a rare condition. In 2002, Rodriguez  reported 3 cases of granular parakeratosis in women in Columbia.
No racial association has been reported for granular parakeratosis. Granular parakeratosis has been reported in blacks and whites.
Most reported cases of granular parakeratosis have occurred in women. Whether this finding represents a reporting bias or a real association is unclear.
The contention that white, middle-aged females are the primary group to experience granular parakeratosis was stressed in a 2013 article. 
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