M.D. Anderson Cancer Center, University of Texas at Houston, Houston, Texas.
Onycholemmal carcinoma is believed to be of trichilemmal origin, and shows differentiation similar to that found in the trichilemmal portion of the hair follicle. Less then 3 cases are currently in the English literature. All reported cases presented in elderly patients and were without recurrence after amputation. Clinical presentation has been varied and can be very subtle. As with most nail tumors, pain is not a common feature. The diagnosis is based on the histology showing an infiltrative growth of atypical keratinocytes, one or more foci of abrupt keratinization, and usually also keratinous cysts devoid of a granular layer. When a cystic component and clear cells predominate, the subtype description of malignant proliferating onycholemmal cyst has been applied. No standard treatment option or follow up has been established.
Recalcitrant unexplained onychodystrophy and recalcitrant paronychia are often frustrating clinical challenges. This patient was fortunate to have an early biopsy of her tumor with unexpected results.
A 73-year-old Hispanic female presented with a 1-year history of a cracked left thumb nail. This gradual split was accompanied by pain, edema, and erythema in the ungal region. Her primary physician treated her with antibiotics for the infection without resolution. This was followed by a course of terbinafine for 3 months with no improvement. Subsequently, she was referred to a dermatologist who began vinegar treatments 3 times a day for 2 months. The dystrophy did not improve. Her nail was removed and a biopsy of the nailbed was performed. The pathological interpretation was that of an invasive carcinoma with onycholemmal features (Figure 1). Examination showed onychodystrophy with no signs of infection, erythema, or edema. No pain was noted on palpitation. An MRI of the left hand noted an enhancing soft tissue lesion involving the distal aspect of the left thumb, extending 2 cm proximal from the tip. Her past medical history included diabetes and hypertension. She is retired but prior work history included field/farm labor, and factory labor. Treatment options were discussed with the patient and distal digit amputation with sentinal lymph node biopsy was performed. The lymph node was negative. On 1-year follow up, the patient remained tumor free.
Onycholemmal carcinoma is believed to be of hair follicle trichilemmal origin . The derivation in the nail region is based on the current acceptance of the hair outer root sheath being the equivalent of the nail bed .
This malignant subungal tumor is rarely reported, with less then 3 cases in the English literature. However, this may be underreported based on the discussion presented by other authors [1, 2]. All reported cases presented in elderly patients and were without recurrence after amputation. Clinical presentation has been varied with paronychia, onychodystrophy, and warty appearances described. Furthermore, simple cracking and fissuring of the nail can be an early sign of tumor. The diagnosis is based on a slow growing ungal lesion. Histologically, it shows an infiltrative growth of atypical keratinocytes, one or more foci of abrupt keratinization, and usually keratinous cysts devoid of a granular layer . When a cystic component and clear cells predominate, the subtype description of malignant proliferating onycholemmal cyst has been applied. Because that presentation demonstrated clear cells but did not have a predominant cystic presentation, these tumors most likely exist in the same spectrum.
In the differential, one must consider benign onycholemmal/trichilemmal lesions, tinea, wart, as well as malignant tumors that may not have a classic single presentation such as amelanotic melanoma . Among these malignancies are keratoacanthoma, onychoamtricoma, and conventional squamous cell carcinoma [1, 3, 4]. Biopsy is crucial in elderly patients with new onset of recalcitrant paronychia, onychodystrophy, or other nail growths/distortions/alterations. Due to the rare nature of this cancer, the incidence of metastasis and spread in this tumor is not known. As noted above, we obtained a one-year follow up evaluation before the patient stopped returning to clinic and did not respond to phone calls or letters. Ideally, long term follow up, as with any other skin cancer, should be the standard of care with such a tumor.
Nail changes need to be closely followed. Both common and rare tumors often present in confounding clinical scenarios with little indication of malignancy. In particular, when chronic changes of the nail plate or nail bed are present, these require more aggressive evaluation. Increased awareness of the subtleties in nail alterations should allow physicians to better assess alternative disease presentations and improve the prognosis .
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3. Telang GH, Jellinek N. Multiple calcified subungual epidermoid inclusions. J Am Acad Dermatol. 2007 ;56(2):336-9. [PubMed]
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