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any anatomic location but commonly arise on the medial thigh, prepuce, neck and
face.
Verrucous (warty) sarcoids are usually less circumscribed than occult sarcoids and
protrude as palpable masses due to an increased dermal neoplastic component.
They may be sessile or pedunculated. The degree of overlying hyperkeratosis and
scaling is variable but there is often a partially or totally alopecic, dry, cauliflower-like
surface. This variant is also relatively slow-growing but a more aggressive
fibroblastic type may emerge following trauma. Verrucous sarcoids need to be
distinguished from squamous papillomas induced by equine papillomavirus and from
chronic frictional irritation. Verrucous sarcoids are most commonly located in the
axillary and inguinal areas.
Fibroblastic sarcoids involve both the dermis and subcutis, with the extent of deep
dermal and subcutaneous infiltration often being underestimated on clinical
examination. This variant typically manifests as a protruberant, firm to fleshy,
ulcerated mass which closely resembles exuberant granulation tissue. It is wellvascularised
and prone to bleed when minimally traumatised. Most sarcoids arising
on the brisket or limbs are of fibroblastic appearance. Fibroblastic sarcoids may
enlarge rapidly over weeks to months and then stabilise and persist for years.
Differential diagnoses for such lesions include, in addition to proud flesh, squamous
cell carcinoma, botryomycosis, habronemiasis, phycomycosis, fibrosarcoma and
peripheral nerve sheath tumour.
Nodular sarcoids usually involve only the subcutis as one or multiple, spherical,
mobile nodules usually covered by intact skin of normal appearance. Intradermal
nodular sarcoids may occasionally be seen and the overlying skin may appear thin
and shiny. Sarcoids involving the palpebral margins are typically nodular and this
variant is also commonly found on the medial thigh, prepuce and inguinal area.
Nodular sarcoids, being well demarcated, are amenable to surgical excision but
incomplete excision (or traumatic ulceration of the overlying skin) may encourage
emergence of a more aggressive fibroblastic variant. Nodular sarcoids may grossly
resemble nodular necrobiosis (equine eosinophilic collagenolytic granuloma) and
other mesenchymal tumours such as melanoma, fibroma or peripheral nerve sheath
tumour.
Mixed sarcoids present with a combination of the gross characteristics of two or
more of the verrucous, fibroblastic and nodular forms and may represent a
transitional phase as a more rapidly growing and locally aggressive neoplasm emerges
from a previously stable focus. Mixed sarcoids are most commonly found in the
axillary and inguinal areas and on the face.
Malevolent sarcoids are rare, highly invasive variants which infiltrate along
lymphatics to produce nodular cording and multiple ulcerated fibroblastic nodules.
The neoplastic tissue may extend along lymphatics to involve regional lymph nodes.
Most malevolent sarcoids have been observed following intereference with a
ACVSC Proceedings Dermatology Chapter Science Week 2005 79