Palmar filiform parakeratotic hyperkeratosis: A report of 2 cases
Published Web Locationhttps://doi.org/10.5070/D33586b4zp
Palmar filiform parakeratotic hyperkeratosis: A report of 2 casesHospital Clínico San Cecilio, Granada, Granada, Spain. firstname.lastname@example.org
Francisco Manuel Almazán-Fernández MD, Jesús Hernández-Gil, Carmen López, José P Macías, Ramón Naranjo
Dermatology Online Journal 15 (10): 12
Palmar filiform parakeratotic hyperkeratosis (PFPH) is a rare dermatosis; hyperkeratotic lesions appear as small spines on the palms and/or soles. Palmar filiform parakeratotic hyperkeratosis has been associated with a variety of malignant tumors and endocrine disorders, although these associations have not been fully demonstrated. We report two new cases of this entity without systemic pathology associated.
Palmar filiform parakeratotic hyperkeratosis (PFPH) is a rare dermatosis; hyperkeratotic lesions appear as small spines on the palms and/or soles. It is an entity that is difficult to classifiy and for this reason it has received many names. It is considered by some authors to be a porokeratosis or keratoderma variant, but others consider it a unique entity. Palmar filiform parakeratotic hyperkeratosis has been associated with a variety of malignant tumors and endocrine disorders, although these associations have not been fully demonstrated. Despite the few cases reported in the literature, PFPH appears to be an underdiagnosed dermatosis because it produces mild symptoms. We report two new cases of this entity without systemic pathology associated.
Case 1. A 65-year-old male, complained about spiny lesions on both hands that evolved over 18 years. They were asymptomatic. His personal history included hypertensive cardiopathy and chronic obstructive pulmonary disease from smoking. One millimeter, filiform hyperkeratotic papules were noted on both palms; the lesions were irregulary distributed and characterized by a slightly yellowish color and rough feel (Fig. 1). No lesions were observed in other locations. The clinical diagnosis was PFPH and we did a biopsy to confirm it. Physical exam, blood count, chemistry panel, amylase, rheumatoid factor, alpha-fetoprotein, carcinoembryonic antigen, CA-15.3, CA-19.9, PSA, TSH, CT-scans, and sigmoidoscopy were done to rule out malignant tumors and metabolic disorders that could be associated with forms of palmar hyperkeratosis. We started local treatment with keratolytic agents and obtained slight improvement.
|Figure 1||Figure 2|
Case 2. A 68-year-old male, complained of lesions on the palms evolving over 6 year. Similarly, the lesions were filiform and hyperkeratotic, resembling small spines (Fig. 2). We did a biopsy that confirmed the clinical diagnosis. As for the first patient, physical examination, blood count, chemistry panel, amylase, rheumatoid factor, alpha-fetoprotein, carcinoembryonic antigen, CA-15.3, CA-19.9, PSA, TSH, CT-scans, and sigmoidoscopy, Chest Xray and sigmoidoscopy were done and were normal. In this case, treatment with topical keratolytics and sanding with a pumice stone successfully smoothed the keratoses.
Palmar filiform parakeratotic hyperkeratosis belongs to type Ia (palm and sole involvement, parakeratosis without orthokeratosis) of the classification of Zarour et al. and McGovern et al. for filiform hyperkeratosis [1, 2]. The first case was described by Brown in 1971 and was called "punctuate keratoderma" . Since then, 30 cases have been described with different characteristics as summarized in Table 1. The terminology used has been quite variable : punctate porokeratotic keratoderma, punctata porokeratosis, Hyperkératose palmo-plantaire filiforme parakératosique, porokeratosis punctata palmaris et plantaris or spiny keratoderma .
Palmar filiform parakeratotic hyperkeratosis has been described more frequently in men who are over 50 years. Clinically it presents as small lesions with a filiform hyperkeratotic morphology that are described by some authors as a "music box spine" ; yellow color and irregular distribution is also described. The condition can affect the palms and soles or only the palms. The feeling when you shake the patient's hand is very distinctive.
Although the diagnosis is clinical, histological study reveals a column of well defined parakeratotic cells that is called a hyperkeratotic column (Fig. 3); generally there is a hypogranular layer . Sometimes the structure may be associated with hair follicles  or with the acrosyringium , similar to porokeratotic eccrine duct nevus [6, 7, 8]. The underlying dermis usually doesn't have any change, but there may be dilated capillaries or a discrete inflammatory infiltrate.
The postulated mechanism of development suggests ectopic and anomalous hair formation, due to the expression of hair cytokeratins, which were detected using antibodies antikeratin AE13 (positive) and AE14 (negative) .
Some familial cases have been described as well as possible associations with malignant tumors (without a parallel course, even 30 years apart)  such as lung, bronchial, renal, colon, or esophageal cancers. Melanoma and chronic lymphocytic leukemia have also been reported. Some cases have been associated with other pathological processes such as dyslipidemia, renal cysts, myelofibrosis , spondylolisthesis or asthma . Given these precedents, it is appropiate to do perform an age-appropriate work up for malignancy .
We report two new cases of filiform parakeratotic hyperkeratosis with palmar involvement. In our opinion it may be an independent and underdiagnosed entity because the patients often do not present with this complaint. The frequency of associated malignant disease is unclear, but, it appears prudent at this time to rule out malignancy.
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