A 37-year-old man came to the dermatology clinic with complaints of skin lesions which were present since birth.
Physical examination revealed two sorts of skin lesions, one type being the brownish hyperkeratotic papules along the Blaschko’s lines (lines of skin cells that are not normally visible), as indicated by the arrowhead and other lesions were the segmental pigmented papules as shown by the arrow.
Skin samples were taken from the hyperkeratotic lesions on the left side of the neck and the right arm for histopathological evaluation. Biopsy results revealed these lesions to be sebaceous nevi, and the pigmented papules were identified as intradermal melanocytic nevi. Results of another sample, taken from the from a lesion on the right forearm, revealed squamous-cell carcinoma.
The man’s disease was diagnosed to be phakomatosis pigmentokeratotica.
Squamous cell carcinoma was excised, and the patient was under scheduled surveillance and regular cancer screening to avoid complications as this rare disease has high risk of developing cancer, which can involve other organs too, besides skin.
Epidermal nevus syndrome is a broad term that represents a number of complex syndromes, characterized by skin lesions called the epidermal nevi, along with other cutaneous and extracutaneous manifestations.
Phakomatosis pigmentokeratotica (PPK) is a rare type of epidermal nevus disorder which was first recognised in 1996. PPK is primarily characterised by both cutaneous and extracutaneous manifestations. The former represents co-existence of nevus sebaceous and speckled lentiginous nevus, whereas the latter mostly include ocular, skeletal and neurological manifestations.
Out of the 30 cases present in literature, only 10 cases have shown extracutaneous features.
The ocular signs include ptosis and strabismus, neurological manifestations may include weakness of one side of the body (hemiparesis), seizures (fits), excessive sweating (hyperhidrosis), and damage of the peripheral nerves causing unpleasant sensations (dysesthesia), and the musculoskeletal abnormalities include muscle weakness, craniofacial defects, deformities of hand, foot and spine such as scoliosis (sideways curvature of the spine) and kyphosis.
Since the disease is rare, quite a few cases have been officially reported in the literature. In the cases reported, no sex predilection has been observed nor is any race found to be more prone to this disease.
There is no definitive treatment of PPK.
Management is mostly symptomatic. Larger lesions are excised, but it can lead to scarring. Carbon dioxide laser has shown some beneficial role in the elimination of these skin lesions.
Only a few cases of phacomatosis pigmentokeratotica have been recorded, and we hope that other clinicians will recognize this unusual condition. There is a small but definite risk of malignant change within the pigmented lesions and the epidermal nevus in later life.
With rare diseases, it is a clinical challenge for physicians to accurately diagnose and manage the patient. PPK being a rare disease is also a challenge for healthcare professionals because, although low, the skin lesions do have malignant potential. Also, there is a small risk of non-dermatological malignancies such as Wilm’s tumour and rhabdomyosarcomas. Having said that, timely diagnosis and management are fundamental.
Akiharu Kubo, M. (2019, October 10). Phakomatosis Pigmentokeratotica. Retrieved from The New England Journal of Medicine: https://www.nejm.org/doi/full/10.1056/NEJMicm1817155
Tadini G, Restano L, Gonzáles-Pérez R, et al. Phacomatosis Pigmentokeratotica: Report of New Cases and Further Delineation of the Syndrome. Arch Dermatol. 1998;134(3):333–337. DOI:10.1001/archderm.134.3.333
Gamayunov, B. N., Korotkiy, N. G., & Baranova, E. E. (2016). Phacomatosis pigmentokeratotica or the Schimmelpenning-Feuerstein-Mims syndrome?. Clinical case reports, 4(6), 564–567. https://doi.org/10.1002/ccr3.570
Hill, V. A., Felix, R. H., Mortimer, P. S., & Harper, J. I. (2003). Phacomatosis pigmentokeratotica. Journal of the Royal Society of Medicine, 96(1), 30–31. https://doi.org/10.1258/jrsm.96.1.30