A novel nonepidermolytic palmoplantar keratoderma: a clinical and histopathologic study of six cases

Functional complexity of intermediate filament cytoskeletons: from structure to assembly to gene ablation

The cell biology of intermediate filament (IF) proteins and their filaments is complicated by the fact that the members of the gene family, which in humans amount to at least 65, are differentially expressed in very complex patterns during embryonic development. Thus, different tissues and cells express entirely different sets and amounts of IF proteins, the only exception being the nuclear B-type lamins, which are found in every cell. Moreover, in the course of evolution the individual members of this family have, within one species, diverged so much from each other with regard to sequence and thus molecular properties that it is hard to envision a unifying kind of function for them. The known epidermolytic diseases, caused by single point mutations in keratins, have been used as an argument for a role of IFs in mechanical "stress resistance," something one would not have easily ascribed to the beaded chain filaments, a special type of IF in the eye lens, or to nuclear lamins. Therefore, the power of plastic dish cell biology may be limited in revealing functional clues for these structural elements, and it may therefore be of interest to go to the extreme ends of the life sciences, i.e., from the molecular properties of individual molecules including their structure at the atomic level to targeted inactivation of their genes in living animals, mouse, and worm to define their role more precisely in metazoan cell physiology.

Hereditary palmoplantar keratoderma (four cases in three generations)

A 39-year-old man reported with progressive thickening of the skin of the hands and feet and an inability to flex his hand. It was largely asymptomatic; however, brisk walking caused excessive sweating, pain, and widening of the fissures on the soles of the feet. He was unable to walk barefooted. According to his mother, the first episode presented with blistering at 7 days of age. Ever since, the condition has steadily worsened to acquire the current status. He was married at the age of 18 years, and had a stillborn child 18 months afterwards. Presently, he has three children, two girls aged 14 and 12 years and a son aged 10 years. Both the daughters are similarly affected. While cataloguing the details of the pattern of inheritance, the mother of the index case was also found to be affected (Fig. 1). The natural history of the disease was identical. Examination of the palms was marked by pronounced thickening of the skin resulting in the masking of palmar creases. The thickening was well demarcated and its margins were prominent and surrounded by an erythematous halo. The color of the skin was yellow and waxy (Fig. 2a). Contractures were present on all the fingers; nevertheless, the deformity of the middle and distal interphalangeal joints of the little finger was prominent. The soles of the feet had a similar morphology. In addition, marked fissuring was obvious (Fig. 2b). His daughters had an identical affliction of the palms and soles. The texture and morphology of the nails were normal. Light microscopy performed on scrapings from the fissures, mounted on 10% potassium hydroxide, revealed mycelia (hyphae) and spores. Hematoxylin and eosin-stained microsections from the palms and soles showed exquisite changes in the epidermis characterized by considerable uniform orthohyperkeratosis. Hypergranulosis and acanthosis were other associated changes. In addition, perinuclear vacuolization and keratohyalin granules of varying sizes and shapes were located at the periphery of the cells. A sparse mononuclear infiltrate was located at the dermo-epidermal junction. Hyphae and spores of fungi were also identified in the stratum corneum (Fig. 3). Itraconazole, 400 mg/day in two equally divided doses, was administered with major meals for 7 days. In addition, high doses of vitamin A (100,000 IU) were given daily for 2 weeks, supplemented by 12% salicylic acid (Salicylix SF12) ointment for daytime application and an ointment containing 6% coal tar and 3% salicylic acid (Salytar) for night-time application. This treatment is useful in recalcitrant cases.

Composite keratohyaline granules in striate keratoderma

The gross, light microscopic, and ultrastructural findings in a 55 year old man was striate keratoderma are presented. There was no family history of the disease. The lesions developed in his late teens and early adult years, and consisted of progressively worsening, raised, hyperkeratotic, linear plaques on the palm and volar surface of the third and fifth fingers bilaterally. There were also painful callosities on both heels, and thick, raised plaques on the heels and lateral plantar surfaces. The epidermis was papillomatous and acanthotic, with marked orthokeratosis, minimal parakeratosis, and a very thickened granular layer. No epidermolysis was seen. Electron microscopy showed increased tonofibrils in the stratum spinosum arranged in wavy, parallel bundles and a granular layer in which normal Odland bodies were present. However, the keratohyaline granules were large, with rounded borders and a striped, alternating, dark and light content characteristic of composite granules. There was diminished contact of the granules with tonofibrils. The transition to the stratum corneum was abrupt. The ultrastructural and genetic features of keratodermas, with special emphasis on the striate type, are reviewed.

Hypergranulotic dyscornification: a distinctive histologic pattern of maturation of epidermal epithelium present in solitary keratoses

Hypergranulotic dyscornification is an appellation proposed to designate a newly recognized distinctive pattern of epidermal maturation that is analogous to other epithelial reaction patterns such as epidermolytic hyperkeratosis, focal acantholytic dyskeratosis, cornoid lamellation, pale-cell acanthosis, and follicular mucinosis. The name "benign hypergranulotic keratosis with dyscornification" is proposed to specify solitary keratoses with digitated epidermal hyperplasia that exhibit this exceptional pattern of cornification. This abnormal type of cornification is characterized by hypergranulosis. A pale-staining basophilic substance is present intercellularly within the upper spinous layer and the hyperplastic granular layer. Overlying the thickened granular layer in foci at tips of epidermal papillations are orthokeratotic mounds of large, dull, eosinophilic staining corneocytes that are sharply demarcated from the thickened granular layer. Basophilic keratohyalin granules are focally retained within these corneocytes. There is overlying compact orthokeratosis that extends across the entire lesion. The compact orthokeratosis is slightly basophilic, and lies below a laminated and basket-weave orthokeratotic stratum corneum. There is a predominantly lymphocytic infiltrate at the base of these neoplasms with some spongiosis. There is parakeratosis focally present in the stratum corneum overlying these individual areas of abnormal cornification. The histopathologic and clinical findings in eight lesions that exhibit hypergranulotic dyscornification, a heretofore undescribed unique pattern of epidermal cornification, are presented.

Abnormal cornified cell envelope formation in mutilating palmoplantar keratoderma unrelated to epidermal differentiation complex

Mutilating palmoplantar keratoderma represents a heterogeneous group of disorders, unified by characteristic mutilation of the fingers or toes, associated with palmoplantar keratoderma. Although loricrin gene mutations were recently reported in Vohwinkel's syndrome and erythrokeratoderma, the genetic basis of mutilating palmoplantar keratoderma is largely unexplored. We studied a family of non-Vohwinkel's syndrome, nonerythrokeratoderma mutilating palmoplantar keratoderma. The proband and his sister were similarly affected. Recessive inheritance was expected from the consanguineous family history. The patients had hyperkeratosis restricted to the palms and the soles. No other body sites were affected. Digital constriction was seen on all the fingers and the mutilation was severe on the distal interphalangeal region of several fingers. Histopathologically, hyperkeratosis without parakeratosis was seen in the lesional skin. Ultrastructural, immunohistochemical, and immunoelectron microscopic analyses revealed malformed cornified cell envelopes, the abnormal intracytoplasmic loricrin retention, and reduced deposition of loricrin to cornified cell envelopes. Involucrin and small proline-rich proteins 1 and 2 were normally distributed. Sequencing of the entire exons and exon-intron borders of loricrin gene of the patients excluded a mutation in loricrin DNA sequence. Linkage analysis excluded the possibility of causative mutation in the epidermal differentiation complex region of 1q21, including loricrin, involucrin, small proline-rich proteins, filaggrin, and trichohyalin. These data confirm the presence of non-Vohwinkel's syndrome mutilating palmoplantar keratoderma phenotype with abnormal loricrin cross-linking at the final stage of cornified cell envelope formation, which is caused by mutations outside the epidermal differentiation complex region.