Multinucleated keratinocytes: A real histologic finding in factitial dermatoses
By Warren R. Heymann, MDJan. 7, 2019
Patients presenting with factitial dermatoses are challenging on every level, and proving the diagnosis may be very difficult because of patient (or parental) denial of the situation. Recently, there have been a few reports of a histologic finding that may help confirm the diagnosis — multinucleated keratinocytes (MKs, also known as multinucleated epidermal giant cells).
Certainly, when epidermal multinucleated giant cells are observed histologically we think first of infectious disorders (e.g. herpes simplex, varicella, herpes zoster, and measles), tumors such as Bowen disease, and rarely of inflammatory disorders including lichen planus and pityriasis rosea. Differentiation between these disorders is usually straightforward based on clinical-pathologic correlation (including peripheral margination of nucleoplasm for herpetic infections, follicular involvement of measles, confirmatory immunohistochemistry, or cultures).
Sweeney et al refer to MKs as “grape cells” (1), although also described as “morula-like” by Amin et al (2). Sweeney et al detail the case of a 16 year-old girl with dermatitis artefacta and a 40 year-old woman with lichen simplex in whom MK cells were found. The authors suggest that MKs are due to chronic rubbing. Amin et al report the cases of 3 teenage girls with dermatitis artefacta; the MKs had up to 20 nuclei and were accompanied by epidermal necrosis. Guitierrez et al describe a 22 year-old woman with a history of depression who presented with painful, rectangular, crusted lesions in different stages of development. Her biopsy displayed MKs with attendant superficial epidermal necrosis (3).
All authors note the obscure etiology of MKs — the presumption is that trauma and manipulation result in syncytial fusion of keratinocytes rather than being due to due abnormalities of mitosis.
It is difficult to speculate on the prevalence of MK in factitial dermatoses. If dermatopathologists appreciate these cells, especially when associated with epidermal necrosis, the question of patient manipulation (which may or may not be factitial) must be entertained. Alternatively, clinicians should be cognizant that performing biopsies on patients with suspect dermatitis artefacta may be valuable in confirming the diagnosis. How this information is relayed to the patient, and management of psychocutaneous disorder, still requires extraordinary skill.
Sweeney SA, et al. Grape cells (multinucleated keratinocytes) in noninfectious dermatoses: Case series and review of the literature. Am J Dermatopathol 2015; 37: e143-6.
Amin SM, et al. Epidermal necrosis with multinucleated keratinocytes: A possible diagnostic clue for dermatitis artefacta. J Eur Acad Dermatol Venereol 2016; 30: e101-2.
Guitierrez D, et al. Epidermal multinucleated keratinocytes: A histopathologic clue to dermatitis artefacta. J Cutan Pathol 2016; 43: 880-3.
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